1. In a very frank, direct, or blunt manner. He was alluding to us being in a serious relationship, so I told him straight out that this was just a fling. You need to let your employees know straight out that they will be fired if they don't meet their quotas each month.

2. At once; without delay or hesitation. When I walked in the room, I knew straight out that something bad had happened between my brothers. When we land, we'll be catching the next flight straight out—there is no layover.

3. Completely and unabashedly. Often hyphenated and used as a modifier before a noun. You don't have to straight out lie to your parents, but you don't have to tell them the whole truth, either. That is a straight-out lie, and you know it!