1) of good name and of good omen
1a) in the latter sense used in taking auguries; but those omens were euphemistically called "euonumos" which in fact were regarded as unlucky, i.e. which came from the left, sinister omens, (for which a good name was desired)
2) left, on the left hand
Part of Speech: adjective
From G2095 and G3686; properly well named (good omened), that is, the left (which was the lucky side among the pagan Greeks); neuter as adverb at the left hand: - (on the) left.
These two sites give similar information, with the definition from several dictionaries and statistics on the use of the word.
Perseus Digital Library
University of Chicago's Logion lexicon
Thayer's dictionary plus other information.
From this site's dictionary (in Italian)
Click on the first column to search for that word as a form of the root εὐώνυμος; click on the second column to search for that grammatical form of the root εὐώνυμος; click on the third column to search for that word and grammatical form; click on the total to search for the root εὐώνυμος.