Definition of staler:
(adj) :
No longer fresh, in reference to food, urine, straw, wounds, etc.
(adj) :
No longer fresh, new, or interesting, in reference to ideas and immaterial things; clichéd, hackneyed, dated.
(adj) :
(in general) Not new or recent; having been in place or in effect for some time.
(adj) :
(law) Unreasonably long in coming, in reference to claims and actions.
(adj) :
Worn out, particularly due to age or over-exertion, in reference to athletes and animals in competition.
(adj) :
(finance) Out of date, unpaid for an unreasonable amount of time, particularly in reference to checks.