| Y | Y-axis (horizontal width of vehicle/structure) |
| Y | Y-axis rate of change |
| Y | out-of-plane velocity |
| Y | pitch axis |
| Y | precision navigation signal |
| Y | yaw |
| Y-T | yaw trim |
| Y/R | yaw roll |
| YAG | yttrium aluminum garnet |
| YE | Deputy for Space Navigation Systems |
| YL | Y-axis of Spacelab |
| YO | Y-axis of orbiter |
| YP | Y-axis of payload |
| YP | yield point |
| YS | Y-axis of solid rocket booster |
| YS | yield strength |
| YSC | yearly spares cost |
| YT | Y-axis of external tank |
| YT | station identification symbol |