loosen/ 'luːsn /

1.vt.[+screw] [ nuts] 
(undo) 拧松

2.vt.[+clothing] [ belt] [ tie etc] 
松开

3.vt.[+restrictions] [ laws] 
(relax) 放松

to loosen one's grip on sth
 [+object] 对紧抓的某物稍稍松手
4.vt.[+power] [ people] 
放松对某物的掌控