21-letter words containing l, o, s, y
- weinberg-salam theory — electroweak theory.
- william of malmesbury — William of, William of Malmesbury.
- x-ray crystallography — the determination of the structure of a crystal by the use of x-ray diffraction.
- yellow lady's-slipper — a showy orchid, Cypripedium calceolus, of eastern North America, having purple-tinged yellow flowers with an inflated lip petal.
- yellow-fever mosquito — a mosquito, Aedes aegypti, that transmits yellow fever and dengue.