A surname from Irish. / A city, the county seat of Holt County, Nebraska, United States.

(Ireland, politics) The policies of Terence O'Neill (1914–1990), fourth Prime Minister of Northern Ireland.

A surname from Irish [in turn originating as a patronymic], a variant of O'Neill.

A proposed space settlement consisting of two cylinders that rotate to provide artificial gravity via centrifugal force.

plural of O'Neill colony

plural of O'Neill cylinder

Synonym of O'Neill cylinder

A supporter of O'Neillism.

plural of O'Neillite

Of or relating to Eugene O'Neill (1888–1953), American playwright who introduced realism into American drama.