stale 1 
(stāl)
(stāl)adj. stal·er, stal·est
1. Having lost freshness, effervescence, or palatability: stale bread; stale air.
2. Lacking originality or spontaneity: a stale joke.
3. Ineffective or uninspired, usually from being out of practice or from having done the same thing for too long.
4. Law Legally unenforceable because of a claimant's delay in seeking enforcement.
tr. & intr.v. staled, stal·ing, stales
To make or become stale.
[Middle English, settled, clear (used of beer or wine), probably from Old French estale, slack, settled, clear, from estaler, to come to a standstill, halt, from estal, standing place, stand, of Germanic origin; see stel- in the Appendix of Indo-European roots.]
stalely adv.
staleness n.