stale

adjective

No longer fresh or pleasant to eat; hard, dry, or past its best.

"The bread went stale overnight."

adjective

Lacking freshness, originality, or interest; uninspired or unventilated.

"The room had stale air and stale ideas."

Thesaurus

Synonyms: dusty, cold, moth-eaten, unoriginal, addled, rancid, corrupt, day-old, spoilt, rotten, hard, bad

Antonyms: fresh