If something slackens or if you slacken it, it becomes slower, less active, or less intense.
例句
Inflationary pressures continued to slacken last month...上个月，通货膨胀的压力继续减小。The Conservative government will not slacken the pace of radical reform.保守党政府不会放慢激进改革的步伐。
V-ERG
(使)松开;(使)放松
If your grip or a part of your body slackens or if you slacken your grip, it becomes looser or more relaxed.
例句
Her grip slackened on Arnold's arm...她紧握着阿诺德的手松开了。Muscles stretch, slacken and relax during childbirth.生孩子的时候，肌肉会拉抻、放松，然后松弛下来。
英汉词典释义
vt. & vi.
(使)松弛
Slacken your legs and slowly lie back.放松双腿, 慢慢向后躺下。
(使某物)放慢, 迟缓
Simon allowed his pace to slacken.西蒙放慢了脚步。
松懈下来；变迟缓
We’ve been really busy, but things are starting to slacken off now.我们忙极了，不过现在事情开始减少了。
英英词典释义
Verb
1. become slow or slower;
"Production slowed"
2. make less active or fast;
"He slackened his pace as he got tired""Don't relax your efforts now"