embryo (n.) Look up embryo at Dictionary.com
"fetus in utero at an early stage of development," mid-14c., from Medieval Latin embryo, properly embryon, from Greek embryon "a young one," in Homer, "young animal," later, "fruit of the womb," literally "that which grows," from assimilated form of en "in" (from PIE root *en "in") + bryein "to swell, be full."