slacken/ 'slækn /

1.vi.[rope+] 
变松

2.vi.[speed+] 
(also: slacken off) 放慢

3.vi.[demand] [ situation+] 
减缓

4.vi.[rain+] 
变小

5.vt.[+grip] 
放松

6.vt.[+speed] 
放慢