21-letter words containing a, l, i, p
- triple superphosphate — superphosphate (def 2).
- triple-superphosphate — Also called acid phosphate. a mixture of calcium acid phosphate and calcium sulfate prepared by treating phosphate rock with sulfuric acid: used chiefly as a fertilizer.
- ulster unionist party — a Northern Irish political party advocating the maintenance of union with the UK
- uncertainty principle — the principle of quantum mechanics, formulated by Heisenberg, that the accurate measurement of one of two related, observable quantities, as position and momentum or energy and time, produces uncertainties in the measurement of the other, such that the product of the uncertainties of both quantities is equal to or greater than h/ 2 π, where h equals Planck's constant.
- up hill and down dale — strenuously and persistently
- west university place — a city in SE Texas.
- white-knuckle paddler — an inexpert and timid canoeist.
- wholesale price index — an indicator of price changes in the wholesale market
- wildlife photographer — someone that specializes in taking photographs of wild animals, especially in their natural habitats, and plants
- with a capital letter — (used to give emphasis to a statement)
- yellow lady's-slipper — a showy orchid, Cypripedium calceolus, of eastern North America, having purple-tinged yellow flowers with an inflated lip petal.