stagnant
Definitions
Having no current or flow and often having an unpleasant smell as a consequence.
Showing no activity, current, or development; sluggish or dull.
Examples
The water in the pond had become stagnant and was covered in a thick layer of algae.
Without new ideas or innovation, the company's growth remained stagnant for several years.
He felt his career was becoming stagnant, so he decided to look for a new challenge.