DICT.TW Dictionary Taiwan

 Knuc·kle, v. i. [imp. & p. p. Knuckled ; p. pr. & vb. n. Knuckling ] To yield; to submit; -- used with down, to, or under.
 To knuckle to. (a) To submit to in a contest; to yield to. [Colloq.] See To knock under, under Knock, v. i.  (b) To apply one's self vigorously or earnestly to; as, to knuckle to work. [Colloq.]