Source : Webster's Revised Unabridged Dictionary (1913)

   9. A body of persons having some common honorary distinction
      or rule of obligation; esp., a body of religious persons
      or aggregate of convents living under a common rule; as,
      the Order of the Bath; the Franciscan order.

            Find a barefoot brother out, One of our order, to
            associate me.                         --Shak.

            The venerable order of the Knights Templars. --Sir
                                                  W. Scott.

   10. An ecclesiastical grade or rank, as of deacon, priest, or
       bishop; the office of the Christian ministry; -- often
       used in the plural; as, to take orders, or to take holy
       orders, that is, to enter some grade of the ministry.

   11. (Arch.) The disposition of a column and its component
       parts, and of the entablature resting upon it, in
       classical architecture; hence (as the column and
       entablature are the characteristic features of classical
       architecture) a style or manner of architectural
       designing.

   Note: The Greeks used three different orders, easy to
         distinguish, Doric, Ionic, and Corinthian. The Romans
         added the Tuscan, and changed the Doric so that it is
         hardly recognizable, and also used a modified
         Corinthian called Composite. The Renaissance writers on
         architecture recognized five orders as orthodox or
         classical, -- Doric (the Roman sort), Ionic, Tuscan,
         Corinthian, and Composite. See Illust. of {Capital}.

   12. (Nat. Hist.) An assemblage of genera having certain
       important characters in common; as, the Carnivora and
       Insectivora are orders of Mammalia.

   Note: The Linn[ae]an artificial orders of plants rested
         mainly on identity in the numer of pistils, or
         agreement in some one character. Natural orders are
         groups of genera agreeing in the fundamental plan of
         their flowers and fruit. A natural order is usually (in
         botany) equivalent to a family, and may include several
         tribes.

   13. (Rhet.) The placing of words and members in a sentence in
       such a manner as to contribute to force and beauty or
       clearness of expression.

   14. (Math.) Rank; degree; thus, the order of a curve or
       surface is the same as the degree of its equation.

   {Artificial order} or {system}. See {Artificial
      classification}, under {Artificial}, and Note to def. 12
      above.

   {Close order} (Mil.), the arrangement of the ranks with a
      distance of about half a pace between them; with a
      distance of about three yards the ranks are in {open
      order}.

   {The four Orders}, {The Orders four}, the four orders of
      mendicant friars. See {Friar}. --Chaucer.

   {General orders} (Mil.), orders issued which concern the
      whole command, or the troops generally, in distinction
      from special orders.

   {Holy orders}.
       (a) (Eccl.) The different grades of the Christian
           ministry; ordination to the ministry. See def. 10
           above.
       (b) (R. C. Ch.) A sacrament for the purpose of conferring
           a special grace on those ordained.

   {In order to}, for the purpose of; to the end; as means to.

            The best knowledge is that which is of greatest use
            in order to our eternal happiness.    --Tillotson.

   {Minor orders} (R. C. Ch.), orders beneath the diaconate in
      sacramental dignity, as acolyte, exorcist, reader,
      doorkeeper.

   {Money order}. See under {Money}.

   {Natural order}. (Bot.) See def. 12, Note.

   {Order book}.
       (a) A merchant's book in which orders are entered.
       (b) (Mil.) A book kept at headquarters, in which all
           orders are recorded for the information of officers
           and men.
       (c) A book in the House of Commons in which proposed
           orders must be entered. [Eng.]

   {Order in Council}, a royal order issued with and by the
      advice of the Privy Council. [Great Britain]

   {Order of battle} (Mil.), the particular disposition given to
      the troops of an army on the field of battle.

   {Order of the day}, in legislative bodies, the special
      business appointed for a specified day.

   {Order of a differential equation} (Math.), the greatest
      index of differentiation in the equation.

   {Sailing orders} (Naut.), the final instructions given to the
      commander of a ship of war before a cruise.

   {Sealed orders}, orders sealed, and not to be opened until a
      certain time, or arrival at a certain place, as after a
      ship is at sea.

   {Standing order}.
       (a) A continuing regulation for the conduct of
           parliamentary business.
       (b) (Mil.) An order not subject to change by an officer
           temporarily in command.

   {To give order}, to give command or directions. --Shak.

   {To take order for}, to take charge of; to make arrangements
      concerning.

            Whiles I take order for mine own affairs. --Shak.

   Syn: Arrangement; management. See {Direction}.

Holy \Ho"ly\, a. [Compar. {Holier}; superl. {Holiest}.] [OE.
   holi, hali, AS. h[=a]lig, fr. h[ae]l health, salvation,
   happiness, fr. h[=a]l whole, well; akin to OS. h?lag, D. & G.
   heilig, OHG. heilac, Dan. hellig, Sw. helig, Icel. heilagr.
   See {Whole}, and cf. {Halibut}, {Halidom}, {Hallow},
   {Hollyhock}.]
   1. Set apart to the service or worship of God; hallowed;
      sacred; reserved from profane or common use; holy vessels;
      a holy priesthood. ``Holy rites and solemn feasts.''
      --Milton.

   2. Spiritually whole or sound; of unimpaired innocence and
      virtue; free from sinful affections; pure in heart; godly;
      pious; irreproachable; guiltless; acceptable to God.

            Now through her round of holy thought The Church our
            annual steps has brought.             --Keble.

   {Holy Alliance} (Hist.), a league ostensibly for conserving
      religion, justice, and peace in Europe, but really for
      repressing popular tendencies toward constitutional
      government, entered into by Alexander I. of Russia,
      Francis I. of Austria, and Frederic William III. of
      Prussia, at Paris, on the 26th of September, 1815, and
      subsequently joined by all the sovereigns of Europe,
      except the pope and the king of England.

   {Holy bark}. See {Cascara sagrada}.

   {Holy Communion}. See {Eucharist}.

   {Holy family} (Art), a picture in which the infant Christ,
      his parents, and others of his family are represented.

   {Holy Father}, a title of the pope.

   {Holy Ghost} (Theol.),the third person of the Trinity; the
      Comforter; the Paraclete.

   {Holy Grail}. See {Grail}.

   {Holy grass} (Bot.), a sweet-scented grass ({Hierochloa
      borealis} and {H. alpina}). In the north of Europe it was
      formerly strewed before church doors on saints' days;
      whence the name. It is common in the northern and western
      parts of the United States. Called also {vanilla, or
      Seneca, grass}.

   {Holy Innocents' day}, Childermas day.

   {Holy Land}, Palestine, the birthplace of Christianity.

   {Holy office}, the Inquisition.

   {Holy of holies} (Script.), the innermost apartment of the
      Jewish tabernacle or temple, where the ark was kept, and
      where no person entered, except the high priest once a
      year.

   {Holy One}.
      (a) The Supreme Being; -- so called by way of emphasis. ``
          The Holy One of Israel.'' --Is. xliii. 14.
      (b) One separated to the service of God.

   {Holy orders}. See {Order}.

   {Holy rood}, the cross or crucifix, particularly one placed,
      in churches. over the entrance to the chancel.

   {Holy rope}, a plant, the hemp agrimony.

   {Holy Saturday} (Eccl.), the Saturday immediately preceding
      the festival of Easter; the vigil of Easter.

   {Holy Spirit}, same as {Holy Ghost} (above).

   {Holy Spirit plant}. See {Dove plant}.

   {Holy thistle} (Bot.), the blessed thistle. See under
      {Thistle}.

   {Holy Thursday}. (Eccl.)
      (a) (Episcopal Ch.) Ascension day.
      (b) (R. C. Ch.) The Thursday in Holy Week; Maundy
          Thursday.

   {Holy war}, a crusade; an expedition carried on by Christians
      against the Saracens in the Holy Land, in the eleventh,
      twelfth, and thirteenth centuries, for the possession of
      the holy places.

Source : WordNet®

holy orders
     n : the sacrament of ordination