The Collaborative International Dictionary
Coversed sine
Coversed sine \Co*versed" sine\ (k?-v?rst" s?n`). [Co- (=co- in co- sine) + versed sine.] (Geom.) The versed sine of the complement of an arc or angle. See Illust. of Functions.
Wiktionary
coversed sine
n. (context trigonometry English) The trigonometric function 1 − sin(''x'').