"to produce young from eggs by incubation," from Middle English hachen (early 13c.), 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" is late 14c. Figurative use (of plots, etc.) is from early 14c. Related: Hatched; hatching.