What is "to talk big"

Big \Big\ (b[i^]g), a. [Compar. Bigger; superl. Biggest.] [Perh. from Celtic; cf. W. beichiog, beichiawg, pregnant, with child, fr. baich burden, Arm. beac'h; or cf. OE. bygly, Icel. biggiligr, (properly) habitable; (then) magnigicent, excellent, fr. OE. biggen, Icel. byggja, to dwell, build, akin to E. be.]

1. Having largeness of size; of much bulk or magnitude; of great size; large. ``He's too big to go in there.''
   --Shak.

2. Great with young; pregnant; swelling; ready to give birth or produce; -- often figuratively.

   [Day] big with the fate of Cato and of Rome.
   --Addison.

3. Having greatness, fullness, importance, inflation, distention, etc., whether in a good or a bad sense; as, a big heart; a big voice; big looks; to look big. As applied to looks, it indicates haughtiness or pride.

   God hath not in heaven a bigger argument.
   --Jer. Taylor.

   Note: Big is often used in self-explaining compounds; as, big-boned; big-sounding; big-named; big-voiced.

   To talk big, to talk loudly, arrogantly, or pretentiously.

   I talked big to them at first.
   --De Foe.

   Syn: Bulky; large; great; massive; gross.