| A | B |
| unicellular | living thing, has one cell |
| unique | there is nothing else like it, it is special |
| universe | consists of everything that exists, including stars and planets |
| bicentennial | two hundredth anniversay of an event |
| biped | an animal that walks on two feet |
| trilogy | a set of three books, plays, films, or stories that are related in subject or theme |
| triple | three times as many; made up of three parts |
| trivial | is not important |
| billingual | a person who speaks two languages |
| triathlon | a long race with three parts, running, swimming, and biking |