Etymology
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incubation (n.)
1610s, "a brooding," from Latin incubationem (nominative incubatio) "a laying upon eggs," noun of action from past participle stem of incubare "to hatch," literally "to lie on, rest on," from in- "on" (from PIE root *en "in") + cubare "to lie" (see cubicle). The literal sense of "sitting on eggs to hatch them" in English is first recorded 1640s.
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incubate (v.)
1640s (transitive), "to brood upon, watch jealously" (figurative); 1721 in literal sense "to sit on (eggs) to hatch them," from Latin incubatus, past participle of incubare "to lie in or upon," also in the figurative sense "brood" (see incubation). Intransitive sense "to sit upon eggs" is from 1755. Related: Incubated; incubating.
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breeding (n.)
early 14c., "hatching, incubation; act of generating or producing;" late 14c., "formation, development, growth;" verbal noun from breed (v.). Meaning "manners, deportment in social life" is from 1590s (commonly short for good breeding), from the notion of "upbringing."
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hatch (v.1)
early 13c., hachen, "to produce young from eggs by incubation," probably from an unrecorded Old English *hæccan, of unknown origin, related to Middle High German, German hecken "to mate" (used of birds). Meaning "to come forth from an egg," also "cause to come forth from an egg" are late 14c. Figurative use (of plots, etc.) is from early 14c. Related: Hatched; hatching.
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breed (v.)
Old English bredan "bring (young) to birth, procreate," also "cherish, keep warm," from West Germanic *brodjan (source also of Old High German bruoten, German brüten "to brood, hatch"), from *brod- "fetus, hatchling," from PIE root *bhreu- "to boil, bubble, effervesce, burn." The etymological notion is incubation, warming to hatch.

Intransitive sense "come into being" is from c. 1200; that of "beget or bear offspring" is from mid-13c. Of livestock, etc., "procure by the mating of parents and rear for use," mid-14c. Sense of "grow up, be reared" (in a clan, etc.) is late 14c.; meaning "form by education" is from mid-15c. Related: Bred; breeding.
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