One of three equals parts (1/3, ⅓, 0.333…).

(US politics) A member or supporter of a third party.

plural of third-grader

Used other than figuratively or idiomatically: see third, country. A country other than two specific countries, especially a country not party to an agreement between two other countries.

plural of Third Worlder

Somebody from the Third World.

plural of third country

plural of third session

plural of third penny

plural of third down