breed: [OE] The Old English verb brēdan came from West Germanic *brōdjan, a derivative of *brōd-, which produced brood. This in turn was based on *brō-, whose ultimate source was the Indo-European base *bhrē- ‘burn, heat’ (its other English descendants include braise, breath, and probably brawn). The underlying notion of breed is thus not ‘reproduction’ so much as ‘incubation, the warmth which promotes hatching’. => braise, brawn, breath, brood
Old English bredan "bring young to birth, carry," also "cherish, keep warm," from West Germanic *brodjan (cognates: Old High German bruoten, German brüten "to brood, hatch"), from *brod- "fetus, hatchling," from PIE *bhreue- "burn, heat" (see brood (n.)). Original notion of the word was incubation, warming to hatch. Sense of "grow up, be reared" (in a clan, etc.) is late 14c. Related: Bred; breeding.