co ‧ sine /ˈkəʊsaɪn $ ˈkoʊ-/ BrE AmE noun [countable] technical
[ Date: 1600-1700 ; Language: Modern Latin ; Origin: cosinus , from co- + Medieval Latin sinus ( ⇨ ↑ sine ) ]
the measurement of an ↑ acute angle in a ↑ triangle with a ↑ right angle , that is calculated by dividing the length of the side next to it by the length of the ↑ hypotenuse ⇨ sine