Meaning

noun ratio of the adjacent side to the hypotenuse of a right-angled triangle

noun lettuce with long dark-green leaves in a loosely packed elongated head

noun an odorless very poisonous gas that is a product of incomplete combustion of carbon

originClipping of cos lettuce, variously derived from the Greek island of Kos and from Arabic خس (ḵass, “lettuce”).

Etymology from Wiktionary, CC BY-SA 3.0