adjective, staler, stalest, verb, staled, staling.
1. not fresh; vapid or flat, as beverages; dry or hardened, as bread.
2. having lost novelty or interest; hackneyed; trite: a stale joke.
3. having lost fresh vigour, quick intelligence, initiative, or the like, as from overstrain, boredom, etc.
4. Law having lost force or effectiveness through absence of action, as a claim.
-- verb (t)
5. to make stale.
-- verb (i)
6. to become stale.
[ME, ? from AF *estale (F étale still (water), from estaler stop]
-- stalely, adverb -- staleness, noun