18-letter words containing o, s, p, r
- 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).
- world championship — an international competition in a particular sport or activity for people all around the world
- 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.