[1] : The Collaborative International Dictionary of English v.0.48

let \let\, v. t. imp.  p. p. let letted le^t"te^d,
   obs.; p. pr.  vb. n. letting. oe. leten, laeten
   past tense lat, let, p. p. laten, leten, lete, as.
   l=aetan past tense l=et, p. p. l=aeten; akin to
   ofries. l=eta, os. l=atan, d. laten, g. lassen, ohg.
   l=azzan, icel. l=ata, sw. lata, dan. lade, goth.
   l=etan, 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.
      1913 webster

            he . . . prayed him his voyage for to let.
                                                  --chaucer.
      1913 webster

            yet neither spins nor cards, ne cares nor frets,
            but to her mother nature all her care she lets.
                                                  --spenser.
      1913 webster

            let me alone in choosing of my wife.  --chaucer.
      1913 webster

   2. to consider; to think; to esteem. obs. --chaucer.
      1913 webster

   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.
      1913 webster

            this irous, cursed wretch
            let this knight's son anon before him fetch.
                                                  --chaucer.
      1913 webster

            he . . . thus let do slay hem all three. --chaucer.
      1913 webster

            anon he let two coffers make.         --gower.
      1913 webster

   4. to permit; to allow; to suffer; -- either affirmatively,
      by positive act, or negatively, by neglecting to restrain
      or prevent.
      1913 webster

   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.
         1913 webster

               pharaoh said, i will let you go.   --ex. viii.
                                                  28.
         1913 webster

               if your name be horatio, as i am let to know it
               is.                                --shak.
         1913 webster

   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.
      1913 webster

   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.
      1913 webster

   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.
         1913 webster

   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.

   to let fly or to let drive, to discharge with violence,
      as a blow, an arrow, or stone. see under drive, and
      fly.

   to let in or to let into.
      a to permit or suffer to enter; to admit.
      b to insert, or imbed, as a piece of wood, in a recess
          formed in a surface for the purpose.

   to let loose, to remove restraint from; to permit to wander
      at large.

   to let off.
      a to discharge; to let fly, as an arrow; to fire the
          charge of, as a gun.
      b to release, as from an engagement or obligation.
          colloq.

   to let out.
      a to allow to go forth; as, to let out a prisoner.
      b to extend or loosen, as the folds of a garment; to
          enlarge; to suffer to run out, as a cord.
      c to lease; to give out for performance by contract, as
          a job.
      d to divulge.

   to let slide, to let go; to cease to care for. colloq. "
      let the world slide." --shak.
      1913 webster
see also:
let letted letting alas late lassitude 
gerund to let alone to let blood to let down to let fly 
to let drive drive fly to let in to let into 
to let loose to let off to let out to let slide 

[2] : The Collaborative International Dictionary of English v.0.48

alone \alone"\, a. all + one. oe. al one all allone, as. =an
   one, alone. see all, one, lone.
   1. quite by one's self; apart from, or exclusive of, others;
      single; solitary; -- applied to a person or thing.
      1913 webster

            alone on a wide, wide sea.            --coleridge.
      1913 webster

            it is not good that the man should be alone. --gen.
                                                  ii. 18.
      1913 webster

   2. of or by itself; by themselves; without any thing more or
      any one else; without a sharer; only.
      1913 webster

            man shall not live by bread alone.    --luke iv. 4.
      1913 webster

            the citizens alone should be at the expense.
                                                  --franklin.
      1913 webster

   3. sole; only; exclusive. r.
      1913 webster

            god, by whose alone power and conversation we all
            live, and move, and have our being.   --bentley.
      1913 webster

   4. hence; unique; rare; matchless. --shak.
      1913 webster

   note: the adjective alone commonly follows its noun.
         1913 webster

   to let alone or to leave alone, to abstain from
      interfering with or molesting; to suffer to remain in its
      present state.
      1913 webster
see also:
all one lone to let alone to leave alone 

Alone >> A Words
Alone, definition of term: Alone
alone_pag1.html