If you describe behaviour as foolhardy, you disapprove of it because it is extremely risky.
例句
When he tested an early vaccine on himself, some described the act as foolhardy...當(dāng)他在自己身上試驗(yàn)還處在初級(jí)階段的疫苗時(shí)，有些人說他的行為是蠻干。It was foolhardy to have refused.拒絕是極不明智的。