noun
- a person who is eccentric, reckless, or mentally unstable; a madcap or harebrained individual
Usage: archaic; informal; often used as a term of mild insult or playful mockery
Examples
- The crackbrains in the tavern were causing a ruckus with their wild schemes.
- He was known as a crackbrain for attempting such a foolish stunt.
- Only a crackbrain would venture into the forest alone at night.
- The crackbrains plotted an elaborate prank on the mayor.
- She dismissed his ideas as the ravings of a crackbrain.