Webster’s Revised Unabridged Dictionary · 1913
Blab
Blab (blăb), v. t. [imp. & p. p. Blabbed; p. pr. & vb. n. Blabbing.] [Cf. OE. blaberen, or Dan. blabbre, G. plappern, Gael. blabaran a stammerer; prob. of imitative origin. Cf. also Blubber, v.] To utter or tell unnecessarily, or in a thoughtless manner; to publish (secrets or trifles) without reserve or discretion. Udall.
And yonder a vile physician blabbing The case of his patient. Tennyson.
Blab, v. i. To talk thoughtlessly or without discretion; to tattle; to tell tales.
She must burst or blab. Dryden.
Blab, n. [OE. blabbe.] One who blabs; a babbler; a telltale. "Avoided as a blab." Milton.
For who will open himself to a blab or a babbler. Bacon.