wane (
http://definr.com/wane)
n : a gradual decline (in size or strength or power or number)
[syn:
ebb,
ebbing]
v 1: grow smaller; "Interest in the project waned" [syn:
decline,
go down]
2: become smaller; "Interest in his novels waned" [ant:
wax]
3: decrease in phase; "the moon is waning" [ant:
wax]