The cardinal number occurring after eighteen and before twenty, represented in Roman numerals as XIX and in Arabic numerals as 19. It is the last/largest of the teens.

(science fiction) An inhabitant of Charon (a moon of Pluto).

(history) A former country in East Africa, a communist government that existed in Ethiopia from 1987 to 1991.

(biochemistry) Reducing the production or effects of thyroid hormones.