Harder or softer, depending

Usage examples of staler.

One of the windows in the smaller of the two rooms was broken, which Remo thought should have gotten rid of the stale smell in the room, until he noticed that pouring through the broken glass were the even staler smells of the great Lobynian outdoors.

Though the zombie stench was fainter, the smell of stale ale was much stronger and much staler than it had been.

I sniffed the scent of Miss Birdie along this well-used route, not the fresh powdery smell that followed in her wake now, but a staler version of it mingled with the scents of many animals.