cash

Cash comes from late Middle French caisse ("money-box"), borrowed from Occitan caissa, from Latin capsa ("box"), itself from capiō ("take, seize"), tracing back to the Proto-Indo-European root *kap-. A second, separate strand comes from Tamil காசு (kācu), ultimately from Sanskrit karsha, a term for a small unit of weight, which shaped the English word for low-denomination coins across South and East Asia.

The French-Latin line shifted from naming the container that held money to naming the money itself. Meanwhile the Tamil-Sanskrit line was extended by English speakers to describe similar small coins used throughout Southeast and East Asia, following Portuguese forms like caixa.

Cash is a doublet of case, chase, and chasse, all descending from the same Latin capsa. It's also worth knowing the word cashier traces back to this same family.