U
- under control
- under no circumstances
- under one's belt
- under one's breath
- under the circumstances
- under the gun
- under the hood
- under the impression
- under the influence
- under the radar
- under the sun
- under the table
- under the weather
- under way
- unsung hero
- until further notice
- up against
- up and down
- up and running
- up close and personal
- up front
- up in the air
- up one's sleeve
- up the ante
- up to
- up to speed
- upper hand
- ups and downs
- upside down
- use up
- used to
- usher in