Entry 2 senses · 2 variants Webster, 1913 Cooper /ko͞op'-ẽr/ · Coop·er · IPA /ˈkupɚ/ n. v. t. 01 n. One who makes barrels, hogsheads, casks, etc. 1. One who makes barrels, hogsheads, casks, etc. 02 v. t. To do the work of a cooper upon; as, to cooper a cask or barrel. imp. & p. p. Coopered; p. pr. & vb. n. Coopering 1. To do the work of a cooper upon; as, to cooper a cask or barrel.