Sinus
来自Big Physics
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late Middle English (in the medical sense): from Latin, literally ‘a recess, bend’.
wiktionary
Unadapted borrowing from Latin sinus(“a bent surface, curve, hollow”). Doublet of sine.
etymonline
sinus (n.)
"hollow curve or cavity in the body," early 15c., from Medieval Latin sinus, from Latin sinus "bend, fold, curve, a bent surface; a bay, bight, gulf; a fold in land;" also "fold of the toga about the breast," hence "bosom," and figuratively "love, affection, intimacy; interior, inmost part;" of unknown origin.
