cost

English cost comes from Middle English costen, from Old French coster/couster, from Medieval Latin cōstō, from Latin cōnstō, meaning 'stand together' — built from com- (together) and stō (stand).

The Latin sense of things 'standing together' — a price and a good balanced against each other — narrowed in Medieval Latin and Old French into the specific idea of what something requires in payment, which passed directly into Middle English costen.

It shares its root stō ('stand') with the com- prefix seen in many 'together' words in Latin-derived English vocabulary, though no other specific English cognate is given in the record.