"large cask," Old English tunne, a general North Sea Germanic word (cf. Old Frisian tunne, Middle Dutch tonne, Old High German tunna, German tonne), also found in Medieval Latin tunna (9c.) and Old French tonne, perhaps from a Celtic source (cf. Middle Irish, Gaelic tunna, Old Irish toun "hide, skin"). Tun-dish (late 14c.) was a funnel made to fit into the bung of a tun.
-- That? said Stephen. -- Is that called a funnel? Is it not a tundish? --
-- What is a tundish? --
--That. The ... the funnel. --
--Is that called a tundish in Ireland? -- asked the dean. -- I never heard the word in my life. --
-- It is called a tundish in Lower Drumcondra -- said Stephen, laughing -- where they speak the best English.--
-- A tundish -- said the dean reflectively. -- That is a most interesting word I must look that word up. Upon my word I must. --
His courtesy of manner rang a little false, and Stephen looked at the English convert with the same eyes as the elder brother in the parable may have turned on the prodigal. [Joyce, "Portrait of the Artist as a Young Man"]