Lingering smell: The lingering smell of coffee filled the room long after the pot was empty.
Lingering (adj.): lasting for a long time; persisting.
It comes from the verb linger, meaning to stay longer than expected or to move slowly.
We lingered over coffee after dinner, talking about our plans for the summer.
She had a lingering feeling of sadness after the movie ended.
The lingering effects of the cold kept him in bed for days.
There was a lingering silence after her unexpected announcement.
He couldn’t shake the lingering doubt about his decision.
The garden had a lingering beauty even in autumn.