Source : Webster's Revised Unabridged Dictionary (1913)

Open \O"pen\, a. [AS. open; akin to D. open, OS. opan, G. offan,
   Icel. opinn, Sw. ["o]ppen, Dan. aaben, and perh. to E. up.
   Cf. {Up}, and {Ope}.]
   1. Free of access; not shut up; not closed; affording
      unobstructed ingress or egress; not impeding or preventing
      passage; not locked up or covered over; -- applied to
      passageways; as, an open door, window, road, etc.; also,
      to inclosed structures or objects; as, open houses, boxes,
      baskets, bottles, etc.; also, to means of communication or
      approach by water or land; as, an open harbor or
      roadstead.

            Through the gate, Wide open and unquarded, Satan
            passed.                               --Milton

   Note: Also, figuratively, used of the ways of communication
         of the mind, as by the senses; ready to hear, see,
         etc.; as, to keep one's eyes and ears open.

               His ears are open unto their cry.  --Ps. xxxiv.
                                                  15.

   2. Free to be used, enjoyed, visited, or the like; not
      private; public; unrestricted in use; as, an open library,
      museum, court, or other assembly; liable to the approach,
      trespass, or attack of any one; unprotected; exposed.

            If Demetrius . . . have a matter against any man,
            the law is open and there are deputies. --Acts xix.
                                                  33.

            The service that I truly did his life, Hath left me
            open to all injuries.                 --Shak.

   3. Free or cleared of obstruction to progress or to view;
      accessible; as, an open tract; the open sea.

   4. Not drawn together, closed, or contracted; extended;
      expanded; as, an open hand; open arms; an open flower; an
      open prospect.

            Each, with open arms, embraced her chosen knight.
                                                  --Dryden.

   5. Hence:
      (a) Without reserve or false pretense; sincere;
          characterized by sincerity; unfeigned; frank; also,
          generous; liberal; bounteous; -- applied to personal
          appearance, or character, and to the expression of
          thought and feeling, etc.

                With aspect open, shall erect his head. --Pope.

                The Moor is of a free and open nature. --Shak.

                The French are always open, familiar, and
                talkative.                        --Addison.
      (b) Not concealed or secret; not hidden or disguised;
          exposed to view or to knowledge; revealed; apparent;
          as, open schemes or plans; open shame or guilt.

                His thefts are too open.          --Shak.

                That I may find him, and with secret gaze Or
                open admiration him behold.       --Milton.

   6. Not of a quality to prevent communication, as by closing
      water ways, blocking roads, etc.; hence, not frosty or
      inclement; mild; -- used of the weather or the climate;
      as, an open season; an open winter. --Bacon.

   7. Not settled or adjusted; not decided or determined; not
      closed or withdrawn from consideration; as, an open
      account; an open question; to keep an offer or opportunity
      open.

   8. Free; disengaged; unappropriated; as, to keep a day open
      for any purpose; to be open for an engagement.

   9. (Phon.)
      (a) Uttered with a relatively wide opening of the
          articulating organs; -- said of vowels; as, the ["a]n
          f["a]r is open as compared with the [=a] in s[=a]y.
      (b) Uttered, as a consonant, with the oral passage simply
          narrowed without closure, as in uttering s.

   10. (Mus.)
       (a) Not closed or stopped with the finger; -- said of the
           string of an instrument, as of a violin, when it is
           allowed to vibrate throughout its whole length.
       (b) Produced by an open string; as, an open tone.

   {The open air}, the air out of doors.

   {Open chain}. (Chem.) See {Closed chain}, under {Chain}.

   {Open circuit} (Elec.), a conducting circuit which is
      incomplete, or interrupted at some point; -- opposed to an
      uninterrupted, or {closed circuit}.

   {Open communion}, communion in the Lord's supper not
      restricted to persons who have been baptized by immersion.
      Cf. {Close communion}, under {Close}, a.

   {Open diapason} (Mus.), a certain stop in an organ, in which
      the pipes or tubes are formed like the mouthpiece of a
      flageolet at the end where the wind enters, and are open
      at the other end.

   {Open flank} (Fort.), the part of the flank covered by the
      orillon.

   {Open-front furnace} (Metal.), a blast furnace having a
      forehearth.

   {Open harmony} (Mus.), harmony the tones of which are widely
      dispersed, or separated by wide intervals.

   {Open hawse} (Naut.), a hawse in which the cables are
      parallel or slightly divergent. Cf. {Foul hawse}, under
      {Hawse}.

   {Open hearth} (Metal.), the shallow hearth of a reverberatory
      furnace.

   {Open-hearth furnace}, a reverberatory furnace; esp., a kind
      of reverberatory furnace in which the fuel is gas, used in
      manufacturing steel.

   {Open-hearth process} (Steel Manuf.), a process by which
      melted cast iron is converted into steel by the addition
      of wrought iron, or iron ore and manganese, and by
      exposure to heat in an open-hearth furnace; -- also called
      the {Siemens-Martin process}, from the inventors.

   {Open-hearth steel}, steel made by an open-hearth process; --
      also called {Siemens-Martin steel}.

   {Open newel}. (Arch.) See {Hollow newel}, under {Hollow}.

   {Open pipe} (Mus.), a pipe open at the top. It has a pitch
      about an octave higher than a closed pipe of the same
      length.

   {Open-timber roof} (Arch.), a roof of which the
      constructional parts, together with the under side of the
      covering, or its lining, are treated ornamentally, and
      left to form the ceiling of an apartment below, as in a
      church, a public hall, and the like.

   {Open vowel} or {consonant}. See {Open}, a., 9.

   Note: Open is used in many compounds, most of which are
         self-explaining; as, open-breasted, open-minded.

   Syn: Unclosed; uncovered; unprotected; exposed; plain;
        apparent; obvious; evident; public; unreserved; frank;
        sincere; undissembling; artless. See {Candid}, and
        {Ingenuous}.

Open \O"pen\, n.
   Open or unobstructed space; clear land, without trees or
   obstructions; open ocean; open water. ``To sail into the
   open.'' --Jowett (Thucyd. ).

         Then we got into the open.               --W. Black.

   {In open}, in full view; without concealment; openly. [Obs.]

Open \O"pen\ v. t. [imp. & p. p. {Opened}; p. pr. & vb. n.
   {Opening}.] [AS. openian. See {Open},a.]
   1. To make or set open; to render free of access; to unclose;
      to unbar; to unlock; to remove any fastening or covering
      from; as, to open a door; to open a box; to open a room;
      to open a letter.

            And all the windows of my heart I open to the day.
                                                  --Whittier.

   2. To spread; to expand; as, to open the hand.

   3. To disclose; to reveal; to interpret; to explain.

            The king opened himself to some of his council, that
            he was sorry for the earl's death.    --Bacon.

            Unto thee have I opened my cause.     --Jer. xx. 12.

            While he opened to us the Scriptures. --Luke xxiv.
                                                  32.

   4. To make known; to discover; also, to render available or
      accessible for settlements, trade, etc.

            The English did adventure far for to open the North
            parts of America.                     --Abp. Abbot.

   5. To enter upon; to begin; as, to open a discussion; to open
      fire upon an enemy; to open trade, or correspondence; to
      open a case in court, or a meeting.

   6. To loosen or make less compact; as, to open matted cotton
      by separating the fibers.

   {To open one's mouth}, {to speak}.

   {To open up}, to lay open; to discover; to disclose.

            Poetry that had opened up so many delightful views
            into the character and condition of our ``bold
            peasantry, their country's pride.''   --Prof.
                                                  Wilson.

Open \O"pen\, v. i.
   1. To unclose; to form a hole, breach, or gap; to be
      unclosed; to be parted.

            The earth opened and swallowed up Dathan, and
            covered the company of Abiram.        --Ps. cvi. 17.

   2. To expand; to spread out; to be disclosed; as, the harbor
      opened to our view.

   3. To begin; to commence; as, the stock opened at par; the
      battery opened upon the enemy.

   4. (Sporting) To bark on scent or view of the game.

Source : WordNet®

open
     adj 1: affording unobstructed entrance and exit; not shut or
            closed; "an open door"; "they left the door open"
            [syn: {unfastened}] [ant: {shut}]
     2: affording free passage or access; "open drains"; "the road
        is open to traffic"; "open ranks" [ant: {closed}]
     3: with no protection or shield; "the exposed northeast
        frontier"; "open to the weather"; "an open wound" [syn: {exposed}]
     4: open to or in view of all; "an open protest"; "an open
        letter to the editor"
     5: used of mouth or eyes; "keep your eyes open"; "his mouth
        slightly opened" [syn: {opened}] [ant: {closed}]
     6: not having been filled; "the job is still open"
     7: accessible to all; "open season"; "an open economy"
     8: not defended or capable of being defended; "an open city";
        "open to attack" [syn: {assailable}, {undefendable}, {undefended}]
     9: (of textures) full of small openings or gaps; "an open
        texture"; "a loose weave" [syn: {loose}]
     10: having no protecting cover or enclosure; "an open boat"; "an
         open fire"; "open sports cars"
     11: opened out; "an open newspaper"
     12: of a set; containing points whose neighborhood consists of
         other points of the same set, or being the complement of
         an open set; of an interval; containing neither of its
         end points [ant: {closed}]
     13: not brought to a conclusion; subject to further thought; "an
         open question"; "our position on this bill is still
         undecided"; "our lawsuit is still undetermined" [syn: {undecided},
          {undetermined}, {unresolved}]
     14: not sealed or having been unsealed; "the letter was already
         open"; "the opened package lay on the table" [syn: {opened}]
     15: without undue constriction as from e.g. tenseness or
         inhibition; "the clarity and resonance of an open tone";
         "her natural and open response"
     16: relatively empty of and unobstructed by fences or hedges or
         headlands or shoals; "in open country"; "the open
         countryside"; "open waters"; "on the open seas"
     17: open and observable; not secret or hidden; "an overt lie";
         "overt hostility"; "overt intelligence gathering" [syn: {overt}]
         [ant: {covert}]
     18: used of string or hole or pipe of instruments [syn: {unstopped}]
         [ant: {stopped}]
     19: not requiring union membership; "an open shop employs
         nonunion workers" [syn: {open(a)}]
     20:  possibly accepting or permitting; "a passage capable of
         misinterpretation"; "open to interpretation"; "an issue
         open to question"; "the time is fixed by the director and
         players and therefore subject to much variation" [syn: {capable},
          {subject}]
     21: not secret; "open plans"; "an open ballot"
     22: without any attempt at concealment; completely obvious;
         "open disregard of the law"; "open family strife"; "open
         hostility"; "a blatant appeal to vanity"; "a blazing
         indiscretion" [syn: {blatant}, {blazing}, {conspicuous}]
     23: affording free passage or view; "a clear view"; "a clear
         path to victory" [syn: {clear}]
     24: lax in enforcing laws; "an open town" [syn: {wide-open}, {lawless}]
     25: openly straightforward and direct without reserve or
         secretiveness; "his candid eyes"; "an open and trusting
         nature"; "a heart-to-heart talk" [syn: {candid}, {heart-to-heart}]
     26: sincere and free of reserve in expression; "Please be open
         with me"
     27: receptive to new ideas; "an open mind"; "open to new ideas"
     28: ready for business; "the stores are open"

open
     n 1: a clear or unobstructed space or expanse of land or water;
          "finally broke out of the forest into the open" [syn: {clear}]
     2: where the air is unconfined; "he wanted to get outdoors a
        little"; "the concert was held in the open air"; "camping
        in the open" [syn: {outdoors}, {out-of-doors}, {open air}]
     3: a tournament in which both professionals and amateurs may
        play
     4: information that has become public; "all the reports were
        out in the open"; "the facts had been brought to the
        surface" [syn: {surface}]

open
     v 1: cause to open or to become open; "Mary opened the car door"
          [syn: {open up}] [ant: {close}]
     2: start to operate or function or cause to start operating or
        functioning; "open a business" [syn: {open up}] [ant: {close}]
     3: become open; "The door opened" [syn: {open up}] [ant: {close}]
     4: begin or set in action, of meetings, speeches, recitals,
        etc.; "He opened the meeting with a long speech" [ant: {close}]
     5: spread out or open from a closed or folded state; "open the
        map"; "spread your arms" [syn: {unfold}, {spread}, {spread
        out}] [ant: {fold}]
     6: make available; "This opens up new possibilities" [syn: {open
        up}]
     7: become available; "an opportunity opened up" [syn: {open up}]
     8: have an opening or passage or outlet; "The bedrooms open
        into the hall"
     9: make the opening move; "Kasparov opened with a standard
        opening"
     10: afford access to; "the door opens to the patio"; "The French
         doors give onto a terrace" [syn: {afford}, {give}]
     11: display the contents of a file or start an application as on
         a computer [ant: {close}]

Source : Free On-Line Dictionary of Computing

open
     
        1. To prepare to read or write a file.  This usually involves
        checking whether the file already exists and that the user has
        the necessary authorisation to read or write it.  The result
        of a successful open is usually some kind of {capability}
        (e.g. a {Unix} {file descriptor}) - a token that the user
        passes back to the system in order to access the file without
        further checks and finally to close the file.
     
        2. Abbreviation for "open (or left) parenthesis" - used when
        necessary to eliminate oral ambiguity.  To read aloud the LISP
        form (DEFUN FOO (X) (PLUS X 1)) one might say: "Open defun
        foo, open eks close, open, plus eks one, close close."
     
        3. Non-proprietary.  An open {standard} is one which can be
        used without payment.
     
        [{Jargon File}]
     
        (1995-01-31)