16-letter words containing p, o, e, r
- world exposition — world's fair.
- writ of subpoena — a legal document commanding the attendance in court, as a witness, of the person on whom it is served, under a penalty
- xenotransplanted — Transplanted by xenotransplantation.
- yellow pikeperch — the walleye, Stizostedion vitreum.
- yellow pimpernel — Lysimachia nemorum
- zero-zero option — (in international nuclear arms negotiations) an offer to remove all intermediate-range nuclear missiles, if the other side will do the same