Ninny/ˈnɪni/ Definition 1 of 1Pro Tip 1/3Colloquial Usage The term 'ninny' is casual and might be offensive in formal situations. My friends laughed when I called myself a ninny for forgetting my keys. Pro Tip 2/3Possible Offense 'Ninny' can be taken as an insult; use it carefully to avoid hurting others. I jokingly called my brother a ninny, but he didn't find it funny. Pro Tip 3/3Self-Deprecation Sometimes used humorously about oneself to show a small mistake or foolishness. I'm such a ninny, I mixed up the meeting dates!