Catch up

Chalk up

Collect up

Dog urine

Drink up

Give up

Pick up

Picked up

Rise up

Spit out

Stand up

Tangled up

Umbilical cord

Unbutton

Unconsciousness

Underwear

Undress (Take off)

Unemployment

Unharness

Unhitch

Unicorn

Unload

Unload (things)

Unpacking

Unsaddle

Unwind

Uphill

Ural Mountains

Uranium (chemical element)

Uranus (planet)

Urine

Urn, Urns

Use

Usurper (usurper of the throne)

Usury

Wake up

Wash up

Wrap up

Wrap up (to warm)