compost (n.)

late 14c., compote, "mixture of stewed fruits, a preserve," from Old French composte "mixture of leaves, manure, etc., for fertilizing land" (13c.), also "condiment," from Vulgar Latin *composita, noun use of fem. of Latin compositus, past participle of componere "to put together," from com "with, together" (see com-) + ponere "to place" (see position (n.)).

The fertilizer sense is attested in English from 1580s, and the French word in this sense is a 19th century borrowing from English. The condiment sense now goes with compote, a later borrowing from French.

compost (v.)

late 15c., "to manure with compost;" 1829, "to make into compost;" from compost (n.). Related: Composted; composting.