Origin: Germanic Old English prefix
Forties has 6 different meanings across 2 categories:
the time of life between 40 and 50
plural of forty
The decade of the 1840s, 1940s, etc.
From or evoking the 41st through 50th years of a century (chiefly the 1940s).
A sea area, in the northern part of the North Sea, where the depth of water is consistently forty fathoms