21-letter words containing e, r, i, o, s
- xeroderma pigmentosum — a rare inherited disease characterized by sensitivity to ultraviolet light, exposure resulting in lesions and tumors of the skin and eyes.
- xilinx netlist format — (language, electronics) (XNF) A Hardware Description Language for electronic circuit design, developed by Xilinx, Inc..
- 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.
- youth training scheme — (formerly, in Britain) a scheme, run by the Training Agency, to provide vocational training for unemployed 16–17-year-olds
- zero-emission vehicle — a vehicle, as an automobile, that does not directly produce atmospheric pollutants. Abbreviation: ZEV.