| A | B |
|---|
| unicycle | one-wheeled vehicle |
| unitard | one piece garment |
| unison | all together as in singing |
| unit | one group as in military |
| unique | one of a kind |
| unicellular | having one cell |
| unilateral | one way talks |
| unidirectional | going in one direction |
| bicycle | two wheeled vehicle |
| biped | two-footed creature |
| bilateral | two sided |
| bicuspid | two pronged tooth |
| bifocals | glasses with two focal lengths |
| biplane | plane with two sets of wings |
| bilingual | speaking two languages |
| biweekly | happening every two weeks |
| biennial | happening every two years |
| bimonthly | happening every two month |
| bicolor | having two colors |
| unify | to bring together |
| triangle | three-sided figure |
| triathalon | race that combines biking, cycling, and running |
| triceratops | dinosaur with three horms |
| tricycle | three-wheeled vehicle |
| trilingual | speaking three languages |
| trilogy | three related books |
| tio | a group of three |
| trisect | to cut into three pieces |
| tripod | three-legged stand |
| trilateral | having or involving three countries, sides, or parties |
