| A | B |
| triplets | three babies born to the same mother at the same time |
| triple | three times as much |
| triplicate | three copies |
| trisect | to cut into three parts |
| tripod | a three-legged stool, table, stand used to hold things, such as a camera |
| trio | a group of three people or things |
| trilogy | three related plays or novels |
| trilingual | able to speak three different languages |
| trilateral | having or involving three sides, countries |
| tricycle | a vehicle with three wheels |
| triceratops | a dinosaur with three horns |
| triathlon | a race with three activities -swimming, biking, running |
| triangle | a shape with three angles |
| trident | a three-pronged spear |
| tricolor | having three colors |
| triennial | happening every three years |