fool·ish 
/ˈfu:lɪʃ/ adjective
/ˈfu:lɪʃ/ adjective [more foolish; most foolish] : having or showing a lack of good sense or judgment : stupid, silly
▪ a foolish decision/mistake ▪ He was wearing a foolish grin. ▪ She's been taking foolish risks. ▪ Those flashy clothes make her look foolish. ▪ She must feel foolish wearing those flashy clothes. ▪ I never thought you'd be foolish enough to believe him.
▪ a foolish decision/mistake ▪ He was wearing a foolish grin. ▪ She's been taking foolish risks. ▪ Those flashy clothes make her look foolish. ▪ She must feel foolish wearing those flashy clothes. ▪ I never thought you'd be foolish enough to believe him.
— fool·ish·ly adverb
▪ He foolishly ignored his parents' advice.
▪ He foolishly ignored his parents' advice.
— fool·ish·ness noun [noncount]
