(of a person) not thinking enough about the effects of what they do; not showing a feeling of responsibility an irresponsible teenager an irresponsible attitude It would be irresponsible to ignore the situation. opposite responsibleExtra examples It is socially irresponsible to refuse young people advice on sexual matters. Their actions were highly irresponsible. This was highly irresponsible behaviour. these extreme and criminally irresponsible policies He’s fun but totally irresponsible. I cannot tolerate this irresponsible attitude. I was a wild, fun-loving, irresponsible teenager at the time. It would be irresponsible to carry on if there really was a problem. It would be irresponsible to ignore the situation.