overvalued idea
n//ˌoʊ.vɚˈvæljud aɪˈdi.ə//övervärdig idé
(psychiatry) A false or exaggerated and sustained belief that is maintained with much less than delusional intensity (i.e., the individual is able to acknowledge the possibility that the ideas may not be true). The belief is accompanied by a strong emotional response, that take priority over all other mental activity.