| umbrella (n.) | a folding cover to protect a person from rain | If it's raining, take an umbrella. |
| unable (adj.) | not able to | The singer is ill and is unable to perform. |
| unbelievable (adj.) | unlikely to be true, hard to believe | We saw an unbelievable variety of flowers. |
| uncertainty (n.) | not being sure about something | His expression showed uncertainty. He couldn't make up his mind. |
| uncomfortable (adj.) | not comfortable | He wore uncomfortable shoes on the hike. Now his feet hurt. |
| under (prep.) | in a position lower than and covered by | We saw lions resting under a tree. |
| underground (n.) | a railway under the ground in a city | The blue underground will get you to the market. |
| understand (v.) | to be familiar with and know about, to know the meaning of something past: understood | I don't understand young people today, with their tattoos and strange clothes. |
| underwater (adj.) | beneath the surface and covered by water | He studied underwater photography. Now he makes nature films. |
| unforgettable (adj.) | not likely to be forgotten | We spent five unforgettable days seeing wild animals on the safari. |
| unfriendly (adj.) | not kind | I thought he liked me, but the last time I saw him he was very unfriendly. |
| unhappy (adj.) | sad, not happy | The dolphins were unhappy because they were kept in a small tank. |
| uniform (n.) | clothing which is the same for all people who work in a certain place or organisation | The Palace Guards wear special uniforms and tall black hats. |
| unique (adj.) | special, having no others like it | The unique materials used for the costumes are not found anywhere else |
| united (adj.) | joined together into one | After a long separation, the mother and her children were united. |
| university (n.) | a school of higher learning that offers professional degrees in addition to college instruction | You can study Chinese in our university. |
| until (prep.) | up to the time of | No one knew where Machu Picchu was until Hiram Bingham found it in 1911. |
| untouched (adj.) | not changed or altered | This desert is still untouched by modern man. |
| unusual (adj.) | not common, not usual, strange | Aren't these designs unusual? I've never seen anything like them. |
| upper (adj.) | closer to the top | The upper floor of the museum is filled with Greek and Roman art. |
| use (v.) | to employ for some purpose | Nobody knows exactly when people began to use skis, but it was a very long time ago. |
| usually (adv.) | most of the time | Lions usually hunt at night, but also sometimes in the daytime. |