certainty, n. [sureness], [confidence], [assurance], [surety]; [fact], [truth]. Antonyms: See uncertainty.

certificate, n. [testimonial], credential, [voucher].

certify, v. assure, [attest], testify to, vouch for.

chafe, v. [rub], [gall], [irritate]; [fret], [fume], [rage].

chaff, n. glumes, hulls, [refuse].

chaff, n. [banter], [raillery], [pleasantry], [jesting], [badinage].

chaff, v. [jest], [banter].

chaffy, a. acerose, palaceous, stramineous.

chagrin, a. [mortification], [abashment], [vexation], [confusion], [discomposure], [humiliation].

chagrin, v. [mortify], [abash], [vex], [confuse], [humiliate].