expression
not by any means; wouldn't do for anything; flatly refusing
Used in strong negative expressions to emphatically refuse or reject something. Often appears in the set phrase まっぴらごめん (I absolutely refuse / I've had enough). The word itself carries a colloquial, somewhat emphatic tone.
See also: まっぴらごめん
こんな寒い日に外に出るのはまっぴらだ。
I absolutely refuse to go outside on a cold day like this.
もう彼のわがままには
I've had enough of his selfishness.
A set phrase meaning 'I absolutely refuse' or 'I've had enough', using まっぴら for emphasis. まっぴら alone is less common and usually appears in similar negative contexts.
The origin is uncertain. It may be related to 真っ平 (まっぴら), literally 'completely flat', used figuratively to mean 'utterly' or 'absolutely', but the exact derivation is unclear.