- ton
- 1379, tonne, unit for measuring the carrying capacity of a ship, originally "space occupied by a tun or cask of wine," thus identical to tun (q.v.). The two words were not differentiated until c.1688. The measure of weight is first recorded 1485; the spelling ton is from 1538, and became firmly established 18c. Tonnage (1422) was originally "tax or duty on wine imported in tuns." Modern tonne (1877) is the Fr. form of the word, adopted for Eng. use to denote a metric ton (1,000 kg.).