1 a of food : no longer good or appealing : no longer fresh
1 b : not clean, clear, or pure : having an unpleasant taste or smell
a room filled with stale smoke
2 : not interesting or new : boring or unoriginal
Their relationship went stale. [=became dull or predictable]
3 : not as strong, effective, or energetic as before
She felt stale [=bored] in her job.