There is a tone to the word stagnant that sounds like what it is: lacking movement, stale, and inactive, especially with exaggerated pronunciation, "staaaagnant."

Stagnant came into use in the 17th century as a description for water or air that wasn't moving or circulating, like in a scum-covered pond or a closed-off room. Often things that are stagnant also have a smell from sitting too long in one place. Not that this happens to everyone, but sitting in front of a TV playing video games without moving more than the fingers can make a person stagnant, sometimes with an accompanying odor.

Definitions of stagnant

adj not growing or changing; without force or vitality

adynamic, undynamic
characterized by an absence of force or forcefulness

adj not circulating or flowing

stagnant water”
(of fluids) not moving or flowing