18-letter words containing s, h, o, r
- working hypothesis — See under hypothesis (def 1).
- world championship — an international competition in a particular sport or activity for people all around the world
- yelloweye rockfish — a red rockfish, Sebastes ruberrimus, of waters along the Pacific coast of North America, having eyes that are yellow and possessed of strong, sawlike bony ridges on the head.
- zermelo set theory — (mathematics) A set theory with the following set of axioms: Extensionality: two sets are equal if and only if they have the same elements. Union: If U is a set, so is the union of all its elements. Pair-set: If a and b are sets, so is {a, b}. Foundation: Every set contains a set disjoint from itself. Comprehension (or Restriction): If P is a formula with one free variable and X a set then {x: x is in X and P(x)}. is a set. Infinity: There exists an infinite set. Power-set: If X is a set, so is its power set. Zermelo set theory avoids Russell's paradox by excluding sets of elements with arbitrary properties - the Comprehension axiom only allows a property to be used to select elements of an existing set.