Crossword clue: a prefix used frequently in composition, signifying well, good, advantageous; -- the opposite of dys-.
1 answer found in Letterora's clue database (Wikidata facts, Open Trivia DB, WordNet and Webster definitions — all licensed sources).
Possible answers
eu
2 letters
web-def
an international organization of European countries formed after World War II to reduce trade barriers and increase coop