Source : Webster's Revised Unabridged Dictionary (1913)

Let \Let\, v. t. [imp. & p. p. {Let} ({Letted} (l[e^]t"t[e^]d),
   [Obs].); p. pr. & vb. n. {Letting}.] [OE. leten, l[ae]ten
   (past tense lat, let, p. p. laten, leten, lete), AS.
   l[=ae]tan (past tense l[=e]t, p. p. l[=ae]ten); akin to
   OFries. l[=e]ta, OS. l[=a]tan, D. laten, G. lassen, OHG.
   l[=a]zzan, Icel. l[=a]ta, Sw. l[*a]ta, Dan. lade, Goth.
   l[=e]tan, and L. lassus weary. The original meaning seems to
   have been, to let loose, let go, let drop. Cf. {Alas},
   {Late}, {Lassitude}, {Let} to hinder.]
   1. To leave; to relinquish; to abandon. [Obs. or Archaic,
      except when followed by alone or be.]

            He . . . prayed him his voyage for to let.
                                                  --Chaucer.

            Yet neither spins nor cards, ne cares nor frets, But
            to her mother Nature all her care she lets.
                                                  --Spenser.

            Let me alone in choosing of my wife.  --Chaucer.

   2. To consider; to think; to esteem. [Obs.] --Chaucer.

   3. To cause; to make; -- used with the infinitive in the
      active form but in the passive sense; as, let make, i. e.,
      cause to be made; let bring, i. e., cause to be brought.
      [Obs.]

            This irous, cursed wretch Let this knight's son anon
            before him fetch.                     --Chaucer.

            He . . . thus let do slay hem all three. --Chaucer.

            Anon he let two coffers make.         --Gower.

   4. To permit; to allow; to suffer; -- either affirmatively,
      by positive act, or negatively, by neglecting to restrain
      or prevent.

   Note: In this sense, when followed by an infinitive, the
         latter is commonly without the sign to; as to let us
         walk, i. e., to permit or suffer us to walk. Sometimes
         there is entire omission of the verb; as, to let [to be
         or to go] loose.

               Pharaoh said, I will let you go.   --Ex. viii.
                                                  28.

               If your name be Horatio, as I am let to know it
               is.                                --Shak.

   5. To allow to be used or occupied for a compensation; to
      lease; to rent; to hire out; -- often with out; as, to let
      a farm; to let a house; to let out horses.

   6. To give, grant, or assign, as a work, privilege, or
      contract; -- often with out; as, to let the building of a
      bridge; to let out the lathing and the plastering.

   Note: The active form of the infinitive of let, as of many
         other English verbs, is often used in a passive sense;
         as, a house to let (i. e., for letting, or to be let).
         This form of expression conforms to the use of the
         Anglo-Saxon gerund with to (dative infinitive) which
         was commonly so employed. See {Gerund}, 2. `` Your
         elegant house in Harley Street is to let.''
         --Thackeray. In the imperative mood, before the first
         person plural, let has a hortative force. `` Rise up,
         let us go.'' --Mark xiv. 42. `` Let us seek out some
         desolate shade.'' --Shak.

   {To let alone}, to leave; to withdraw from; to refrain from
      interfering with.

   {To let blood}, to cause blood to flow; to bleed.

   {To let down}.
      (a) To lower.
      (b) To soften in tempering; as, to let down tools,
          cutlery, and the like.

Source : WordNet®

let
     v 1: make it possible through a specific action or lack of action
          for something to happen; "This permits the water to rush
          in"; "This sealed door won't allow the water come into
          the basement"; "This will permit the rain to run off"
          [syn: {allow}, {permit}] [ant: {prevent}]
     2: actively cause something to happen; "I let it be known that
        I was not interested"
     3: consent to, give permission; "She permitted her son to visit
        her estranged husband"; "I won't let the police search her
        basement"; "I cannot allow you to see your exam" [syn: {permit},
         {allow}, {countenance}] [ant: {forbid}, {forbid}]
     4: cause to move; cause to be in a certain position or
        condition; "He got his squad on the ball"; "This let me in
        for a big surprise"; "He got a girl into trouble" [syn: {get},
         {have}]
     5: leave unchanged; "let it be"
     6: grant use or occupation of under a term of contract; "I am
        leasing my country estate to some foreigners" [syn: {lease},
         {rent}]
     [also: {letting}]

letting
     n : property that is leased or rented out or let [syn: {lease},
         {rental}]

letting
     See {let}