caddy: [18] Caddy comes ultimately from Malay katī, which was a measure of weight equal to about 0.6 kilos or 1½ pounds: it was thus originally ‘container which holds one caddy of tea’. English acquired the word in the 16th century as catty, and it is not altogether clear where the -dd- spelling came from. It has no connection with the golfer’s caddie (see CADET). [caddy etymology, caddy origin, 英语词源]
"small box for tea," 1792, from Malay kati a weight equivalent to about a pound and a third (in English from 1590s as catty), adopted as a standard mid-18c. by British companies in the East Indies. Apparently the word for a measure of tea was transferred to the chest it was carried in.