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.

Used to justly praise someone for their achievement or contribution.

Xenopus petersii, a species of central African frog.

(physics) A quantity that measures an object or substance's resistance to being deformed elastically (i.e. non-permanently) when a stress is applied to it, defined as the ratio of stress to strain.