mentally deranged; demented; insane.

senseless; impractical; totally unsound

a crazy scheme.

Informal . intensely enthusiastic; passionately excited

crazy about baseball.

Informal . very enamored or infatuated (usually fol. by about )

He was crazy about her.

Informal . intensely anxious or eager; impatient

I'm crazy to try those new skis.

Informal . unusual; bizarre; singular

She always wears a crazy hat.

Slang . wonderful; excellent; perfect

That's crazy, man, crazy.

likely to break or fall to pieces.

weak, infirm, or sickly.

having an unusual, unexpected, or random quality, behavior, result, pattern, etc.

a crazy reel that spins in either direction.

Slang . an unpredictable, nonconforming person; oddball

a house full of crazies who wear weird clothes and come in at all hours.

the crazies, Slang . a sense of extreme unease, nervousness, or panic; extreme jitters

The crew was starting to get the crazies from being cooped up belowdecks for so long.

like crazy

Slang . with great enthusiasm or energy; to an extreme

We shopped like crazy and bought all our Christmas gifts in one afternoon.

with great speed or recklessness

He drives like crazy once he's out on the highway.

noun

brainsickness , dementia , derangement , disturbance , insaneness , lunacy , madness , mental illness , psychopathy , unbalance , absurdity , folly , foolery , idiocy , imbecility , insanity , nonsense , preposterousness , senselessness , silliness , tomfoolery , zaniness