mid-15c., from Latin germinationem (nominative germinatio) "sprouting forth, budding," noun of action from past participle stem of germinare "to sprout, put forth shoots," from germen (genitive germinis) "a sprout or bud" (see germ).
c.1600, probably a back-formation from germination. Earlier germynen (mid-15c.) was from Latin germinare. Figurative use from 1640s. Related: Germinated; germinating.