緩む

also 弛む

1. godan verb, intransitive to become loose; to slacken (e.g. rope)
2. to become less tense; to relax; to let one's guard down
3. to slacken (e.g. coldness, supervision); to become lax
4. to become softer (e.g. ground, facial expression); (of ice) to partially melt
5. to decrease (e.g. speed)
6. (of a market price) to go down slightly