Source : Webster's Revised Unabridged Dictionary (1913)

Gab \Gab\, n. [Cf. {Gaff}.] (Steam Engine)
   The hook on the end of an eccentric rod opposite the strap.
   See. Illust. of {Eccentric}.

Gab \Gab\, n. [OE. gabbe gabble, mocking, fr. Icel. gabb
   mocking, mockery, or OF. gab, gabe; perh. akin to E. gape, or
   gob. Cf. {Gab}, v. i., {Gibber}.]
   The mouth; hence, idle prate; chatter; unmeaning talk;
   loquaciousness. [Colloq.]

   {Gift of gab}, facility of expression. [Colloq.]

Gab \Gab\, v. i. [OE. gabben to jest, lie, mock, deceive, fr.
   Icel. gabba to mock, or OF. gaber. See 2d {Gab}, and cf.
   {Gabble}.]
   1. To deceive; to lie. [Obs.] --Chaucer.

   2. To talk idly; to prate; to chatter. --Holinshed.

Source : WordNet®

gab
     n : light informal conversation for social occasions [syn: {chitchat},
          {small talk}, {gabfest}, {gossip}, {tittle-tattle}, {chin-wag},
          {chin-wagging}, {causerie}]