不理智的词可以用 "irrational" 来表示。例如：

"His decision to quit his job without having a backup plan was irrational." (他没有备用计划就轻易地辞职是不理智的。)

其他可以表示不理智的词还有 "unreasonable," "illogical," "crazy," "foopsh," "idiotic," 等。