Webster's Revised Unabridged Dictionary · 1913

Fifteen

Fifteen , adjective

[Old English fiftene, Anglo-Saxon fīftȳne, fīftēne. See Five, and Ten, and compare Fifty.]

Five and ten; one more than fourteen.

Fifteen , noun

1.
The sum of five and ten; fifteen units or objects.
2.
A symbol representing fifteen units, as 15, or xv.