| a combining form meaning “good,” “well,” occurring chiefly in words of Greek origin (eupepsia); in scientific coinages, esp. taxonomic names, it often has the sense “true, genuine” (eukaryote) |

| eu- pref.
[Middle English, from Latin, from Greek; see (e)su- in Indo-European roots.] |
eu- pref.
Good; well; true: eupepsia.
A derivative of a specified substance: euglobulin.