18-letter words containing n, i, e, s, p, o
- under-compensation — to compensate or pay less than is fair, customary, or expected.
- universal coupling — a coupling between rotating shafts set at an angle to one another, allowing for rotation in three planes.
- up to one's tricks — If you say that someone is up to their tricks or up to their old tricks, you disapprove of them because they are behaving in the dishonest or deceitful way in which they typically behave.
- visiting professor — a professor from another institution invited to teach at a university or college for a limited period, usually for a semester or one academic year.
- 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
- wild passionflower — the maypop, Passiflora incarnata.
- wilson's phalarope — a phalarope, Phalaropus tricolor, that breeds in the prairie regions of North America and winters in Argentina and Chile.
- wireless telephone — Now Rare. radiotelephony.
- wireless telephony — Now Rare. radiotelephony.
- women at point sur — a narrative poem (1927) by Robinson Jeffers.
- working hypothesis — See under hypothesis (def 1).