The Collaborative International Dictionary of English v.0.48:

Fain \Fain\, a. [OE. fain, fagen, AS. f[ae]gen; akin to OS.
   fagan, Icel. faginn glad; AS. f[ae]gnian to rejoice, OS.
   fagan[=o]n, Icel. fagna, Goth. fagin[=o]n, cf. Goth.
   fah[=e]ds joy; and fr. the same root as E. fair. Srr Fair,
   a., and cf. Fawn to court favor.]
   1. Well-pleased; glad; apt; wont; fond; inclined.
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            Men and birds are fain of climbing high. --Shak.
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            To a busy man, temptation is fainto climb up
            together with his business.           --Jer. Taylor.
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   2. Satisfied; contented; also, constrained. --Shak.
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            The learned Castalio was fain to make trechers at
            Basle to keep himself from starving.  --Locke.
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The Collaborative International Dictionary of English v.0.48:

Fain \Fain\, adv.
   With joy; gladly; -- with wold.
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         He would fain have filled his belly with the husks that
         the swine did eat.                       --Luke xv. 16.
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         Fain Would I woo her, yet I dare not.    --Shak.
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The Collaborative International Dictionary of English v.0.48:

Fain \Fain\, v. t. & i.
   To be glad; to wish or desire. [Obs.]
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         Whoso fair thing does fain to see.       --Spencer.
   [1913 Webster] Faineance

WordNet (r) 3.0 (2006):

fain
    adv 1: in a willing manner; "this was gladly agreed to"; "I
           would fain do it" [syn: gladly, lief, fain]
    adj 1: having made preparations; "prepared to take risks" [syn:
           disposed(p), fain, inclined(p), prepared]