To not know at all. / To be mistaken; to not have a correct idea.

(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.

Idea behind a business, central to the generation of revenue.

(US, colloquial, often preceded by hey) Used to express surprise or dissatisfaction with an action or statement of another person, especially to that person.

(informal) To not know; to have no idea.

(chiefly in the negative) To have any knowledge (about something); have a clue. / Used other than figuratively or idiomatically: see have, first, idea.

To not know anything about something.

Alternative spelling of overvalued idea

(informal) To get the inspiration or temptation to do something unwise.

plural of business idea