adjective / noun
loony
LOO-nee/ˈluːni/
Crazy or foolish, or a person regarded that way.
His loony plan covers the bicycle with tiny cocktail umbrellas.

Etymology
Loony shortens lunatic, which originally described insanity believed to vary with the moon. The shortened adjective broadened into an informal description of someone or something crazy, silly, or eccentric.
In context
there's a loony old coot named a pac-mule parker yeah we ran into him he's got the mistaken idea that he owns practically all the mining country around here and has to protect it against trespassers
More examples
- She called the proposal loony.
- He regretted calling the protesters loonies.
- The idea sounded loonier every minute.
Forms
loony · loonies · loonier · looniest
Similar words
- foolish
- A less insulting description of poor judgment.
- absurd
- Emphasizes lack of sense rather than presumed mental state.