Translation guide
The English verb 'loosen' covers several distinct actions: making something physically less tight, relaxing rules or restrictions, and becoming less tense. Japanese uses different verbs depending on what is being loosened and whether the action is intentional or spontaneous.
To intentionally reduce tightness of a fastened object.
To make regulations or supervision less strict.
To relax physically or emotionally.
Transitive verb for loosening stiff muscles or tension. Often used for massage or stretching.
To break up compacted earth or similar substances.
Used for loosening soil, tangled threads, etc.
The screw came loose.
Can also be used for relaxing rules or discipline, but less formal than 緩和する.
loosen the rules
loosen up one's shoulders
Intransitive verb meaning muscles or tension loosen naturally.
The tension loosened.
Can describe a grip or facial expression relaxing.
one's expression loosens/relaxes
loosen the soil
The screw loosened by itself.
While 緩める is a common translation, it does not work for loosening muscles or soil. Use ほぐす for those contexts.