13-letter words containing a, s, t, o, n, i
- winterisation — Non-Oxford British standard spelling of winterization.
- within reason — a basis or cause, as for some belief, action, fact, event, etc.: the reason for declaring war.
- wordsworthian — William, 1770–1850, English poet: poet laureate 1843–50.
- working asset — invested capital that is comparatively liquid.
- xanthochroism — a condition in certain animals, esp aquarium goldfish, in which all skin pigments other than yellow and orange disappear
- xiphiplastron — the fourth lateral plate of a turtle's plastron
- zinjanthropus — the genus to which Australopithecus boisei was formerly assigned.