The Collaborative International Dictionary of English v.0.48:

Entreat \En*treat"\, v. t. [imp. & p. p. Entreated; p. pr. &
   vb. n. Entreating.] [OE. entreten to treat, request, OF.
   entraiter to treat of; pref. en- (L. in) + traitier to treat.
   See Treat.]
   1. To treat, or conduct toward; to deal with; to use. [Obs.]
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            Fairly let her be entreated.          --Shak.
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            I will cause the enemy to entreat thee well. --Jer.
                                                  xv. 11.
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   2. To treat with, or in respect to, a thing desired; hence,
      to ask earnestly; to beseech; to petition or pray with
      urgency; to supplicate; to importune. "Entreat my wife to
      come." "I do entreat your patience." --Shak.
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            I must entreat of you some of that money. --Shak.
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            Some late visitor entreating entrance at my chamber
            door.                                 --Poe.
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            Isaac entreated the Lord for his wife. --Gen. xxv.
                                                  21.
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   3. To beseech or supplicate successfully; to prevail upon by
      prayer or solicitation; to persuade.
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            It were a fruitless attempt to appease a power whom
            no prayers could entreat.             --Rogers.
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   4. To invite; to entertain. [Obs.] "Pleasures to entreat."
      --Spenser.

   Syn: To beseech; beg; solicit; crave; implore; supplicate.
        See Beseech.
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The Collaborative International Dictionary of English v.0.48:

Entreat \En*treat"\, v. i.
   1. To treat or discourse; hence, to enter into negotiations,
      as for a treaty. [Obs.]
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            Of which I shall have further occasion to entreat.
                                                  --Hakewill.
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            Alexander . . . was first that entreated of true
            peace with them.                      --1 Mac. x.
                                                  47.
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   2. To make an earnest petition or request.
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            The Janizaries entreated for them as valiant men.
                                                  --Knolles.
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The Collaborative International Dictionary of English v.0.48:

Entreat \En*treat"\, n.
   Entreaty. [Obs.] --Ford.
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WordNet (r) 3.0 (2006):

entreat
    v 1: ask for or request earnestly; "The prophet bid all people
         to become good persons" [syn: bid, beseech, entreat,
         adjure, press, conjure]

Moby Thesaurus II by Grady Ward, 1.0:

33 Moby Thesaurus words for "entreat":
   adjure, appeal, appeal to, beg, beseech, blandish, call for help,
   call on, call upon, clamor for, coax, conjure, crave, cry for,
   cry on, cry to, impetrate, implore, importune, imprecate, invoke,
   kneel to, obtest, pester, plague, plead, plead for, pray, press,
   run to, supplicate, urge, wheedle