Old English ofen "furnace, oven, chamber or receptacle in which food is baked or cooked by continuous heat radiated from the structure," from Proto-Germanic *ukhnaz (source also of Old Frisian, Dutch oven, Old High German ovan, German Ofen, Old Norse ofn, Old Swedish oghn, Gothic auhns), from PIE *aukw- "cooking pot" (source also of Sanskrit ukhah "pot, cooking pot," Latin aulla "pot," Greek ipnos), originally, perhaps, "something hollowed out."
Oven-bird (1825) is a name given to various species that build arched or roofed oven-shaped nests. In slang, in reference to a woman, to have (something) in the oven "to be pregnant" is attested from 1962. Ovenware "dishes that can be used for cooking in an oven" is by 1916 in Pyrex ads.