Where does “kosinus” come from?

kosinus (Polish) comes from New Latin cosinus, from Latin complementi sinus.

Ancestry of “kosinus”, step by step

StepLanguageWordMeaning
1New Latincosinusco-pocket
2Latincomplementi sinus
Every word from Latin complementi sinusEvery word from New Latin cosinus
kosinus — Etymology, Origin & Word History | Etymology Explorer