Embryo

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late Middle English: via late Latin from Greek embruon ‘fetus’, from em- ‘into’ + bruein ‘swell, grow’.

wiktionary

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Borrowed from Medieval Latin embryō, from Ancient Greek ἔμβρυον(émbruon, “fetus”), from ἐν(en, “in-”) + βρύω(brúō, “I grow, swell”). Possibly related to Hebrew עֻבָּר‎ (“fetus, embryo”) ('ʊbar).

etymonline

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embryo (n.)

"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."