expression, noun-modifying (irregular)
gutsy; fearless; unwavering
Describes a person who remains calm and resolute under pressure; literally 'with a settled stomach', implying inner strength. Used prenominally to modify a noun.
彼は腹の据わった男だ。
He is a gutsy man.
あの状況で笑っていられるなんて、腹の据わった人だね。
Being able to laugh in that situation, she's a fearless person.
Literally 'stomach has settled', from the idea that a calm stomach reflects a composed mind. The expression is a fixed prenominal phrase derived from the verb 腹が据わる (to be resolute).