maniac
n. countable C1 Advanced US //ˈmeɪniˌæk// UK //mˈeɪnɪˌæk// ma·ni·ac
n. someone who behaves in a wild, dangerous, or extremely foolish way. You might use this word to describe a person who is acting out of control or driving too fast.
n. a person exhibiting extremely wild, violent, or irrational behaviour. Often used hyperbolically in modern speech to describe someone acting recklessly or with excessive enthusiasm.
Slow down, you are driving like a maniac.
The crowd went wild, screaming like a bunch of maniacs when the band finally took the stage.
From mania + -ac. Borrowed from French maniaque, from Late Latin maniacus, from Ancient Greek μανιακός (maniakós), adjectival form of μανία (manía, “madness”). Compare manic.
Usage
Often used in the prepositional phrase 'like a maniac' to modify verbs of action or movement.