| 5000 Vocabulary List for Visiting Scholars in the USA - Page 623 | |||
| Word | Type | Used in a Sentence | Synonym |
| unknown | adj. | She was an unknown scholar. | obscure |
| unless | conj. | Unless you can pay, do not order one. | except |
| unlike | adj. | He was unlike any other person. | different |
| prep. | Unlike my boss, he asked our opinion. | different than | |
| unnecessary | adj. | It was an unnecessary precaution. | unneeded |
| unpleasant | adj. | We just had an unpleasant experience. | disagreeable |
| unreasonable | adj. | Theirs was an unreasonable demand. | unrealistic |
| untie | verb | We untied his hands and let him go free. | unfastened |
| until | prep. | I will love you until the end of time. | up to the time of |
| conj. | I agreed until you said that. | before | |
| unusual | adj. | It was indeed an unusual day. | unique |
| up | prep. | The cat ran up the tree. | to higher place |
| adv. | He is moving up in the world. | higher position | |