on. a nonmetallic bivalent element that is normally a colorless odorless tasteless nonflammable diatomic gas; constitutes 21 percent of the atmosphere by volume; the most abundant element in the earth's crust on. the 15th letter of the Roman alphabet on. the blood group whose red cells carry neither the A nor B antigens o leveln. the basic level of a subject taken in school o ringn. a gasket consisting of a flat ring of rubber or plastic; used to seal a joint against high pressure o'brienn. Irish writer (born in 1932) o'caseyn. Irish playwright (1880-1964) o'clockr. according to the clock o'connorn. United States writer (1925-1964) o'err. throughout a period of time o'flahertyn. Irish writer of short stories (1896-1984) o'haran. United States writer (1905-1970) o'keeffen. United States painter (1887-1986) o'neilln. United States playwright (1888-1953) o'toolen. British actor (born in Ireland in 1932)
