Madcap/ˈmædkæp/ Definition 1 of 2Pro Tip 1/3Informal Tone Used in casual settings, not in serious or formal conversations. They embarked on a madcap journey across the city. Pro Tip 2/3Often Humorous Describes actions or behaviors that are intended to be amusing or entertaining. Her madcap antics always liven up the party. Pro Tip 3/3Impulsive Actions Highlights behavior without careful thought or planning, done on impulse. A madcap decision led them to a night they'd never forget.