淀

If you get caught in an eddy, the water seems determined to pull you in. (Edit: As Sam79's post says, "eddy" isn't a good keyword. This kanji refers to things that stop moving such as water, air, speech, etc. "Stagnate" has been used elsewhere, so maybe "go stale," "stall," or "stop moving" would be suitable keywords. Story: The water reaches a determined position and stops moving).

Source: Kanji Koohii community