あたぼうあたぼうMeanings1na-adjectivenatural; reasonable; obviousslangSlang term derived from 当り前 and べらぼうめ. Used to express that something is a matter of course or goes without saying, often with a rough or emphatic tone.See also: 当り前 · べらぼうめそんなのあたぼうだろ。That's obvious, isn't it?あたぼうな話はなしだ。It's a natural story.