NINETEEN
nineteen, xix
(adjective) being one more than eighteen
nineteen, XIX
(noun) the cardinal number that is the sum of eighteen and one
Source: WordNet® 3.1
Etymology
Numeral
nineteen
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".
Source: Wiktionary
Nine"teen`, a. Etym: [AS. nigont, nigont. See Nine, and Ten.]
Definition: Nine and ten; eighteen and one more; one less than twenty; as,
nineteen months.
Nine"teen`, n.
1. The number greater than eighteen by a unit; the sum of ten and
nine; nineteen units or objects.
2. A symbol for nineteen units, as 19 or xix.
Source: Webster’s Unabridged Dictionary 1913 Edition