IPA: //stæɡˈnæntli//
KK: /ˈstæɡnəntli/
In a way that shows no movement or progress; remaining still or inactive.
The water in the pond was stagnantly still, with no signs of life.
Stagnantly → It is formed from "stagnant" (from Latin "stagnans", meaning standing water) and the suffix "-ly" (meaning in a manner of). The word "stagnantly" describes the manner of being inactive or not flowing, similar to standing water.
Think of water that is 'standing' still ('stagnant') and how it doesn't move, which helps you remember that 'stagnantly' means in a manner that is inactive or not flowing.
No commonly confused words.