Unhappy, a.
1. Not happy or fortunate; unfortunate; unlucky; as, affairs have taken an unhappy turn.
2. In a degree miserable or wretched; not happy; sad; sorrowful; as, children render their parents unhappy by misconduct.
3. Marked by infelicity; evil; calamitous; as, an unhappy day. "The unhappy morn." Milton.
4. Mischievous; wanton; wicked. [Obs.] Shak. -- Un*hap"pi*ly, adv. -- Un*hap"pi*ness, n.
Shades of meaning
Fernald lists unhappy only as an antonym, under fortunate.
He lists it without comment; the entries above explain its neighbors.
Synonyms
none given