quinzena

Etymology
From +.

Noun

 * 1) a set of fifteen like objects
 * 2) a period of fifteen consecutive days
 * 3) fortnight

Usage notes
While the literal meaning of quinzena as a period of time is fifteen days, it is also used to describe just two weeks with 14 days or the period from the 16th day of a month to the last day of the month, which can be from 13 to 16 days long.

Etymology
..

Noun

 * 1) a period of fifteen consecutive days