18-letter words containing p, o, r, t, y
- western isles pony — a breed of large pony, typically grey, with a dense waterproof coat. The only surviving variety is the Eriskay pony
- white iron pyrites — marcasite
- wireless telephony — Now Rare. radiotelephony.
- withdrawal symptom — effects of stopping a drug
- work-study program — a program enabling high-school or college students to combine academic work with actual job experience.
- working hypothesis — See under hypothesis (def 1).
- x-ray spectrometer — a spectrometer using x-rays to activate the inner electrons of an atom in order to separate and identify the chemical constituents of a substance and their concentrations.
- x-ray spectrometry — the use of an x-ray spectrometer.