for a minute—
1. very briefly; for a short time:
- Could I borrow your English dictionary for a minute, please?
2. for one moment:
- The police moved to protect him and for a minute it seemed as if they were going to put him into a car.
not for a minute—(emphatic) absolutely never (also: not for one minute):
- He may have considered it but not for a minute did he believe that Scotland would win.