Ya
- YAG
- A widely used solid-state crystal which is composed of yttrium and aluminium oxides which is doped with a small amount of the rare-earth neodymium.
- Yagi Antenna
- A directional antenna consisting of a rod pointed in the direction of the transmission/reception and several cross bars.
- Yalow, Rosalyn
- Co-inventer of radioimmunoassay for which she won the 1977 Nobel Proze in Medicine.
- Yard
- The yard was a unit of length of the British system of units.
- Yardstick
- A wooden rule 36" long.
- Yarn
- Continuously twisted fibres or strands suitable for use in weaving into fabrics.
- Yaw
- The rotation of a body about a vertical axis.
- Yaw Error
- Positioning error resulting from a yaw motion.
- Yawing Moment
- A moment that tends to rotate an aircraft about a vertical axis.
- y axis
- The vertical axis in the plane.