1. having frequent changes in mood or emotional state; unpredictable in temperament
2. sad, gloomy, or sullen in mood

Examples

• The teenager became moody and difficult to talk to.
• She’s been moody all week since the argument.
• His moody behavior made it hard to predict his reactions.
• The artist was known for being moody and temperamental.
• Don’t take it personally – he’s just in a moody phase.
• The moody sky threatened rain all afternoon.
• Her moody silence worried her friends.