/ˈslækən ||; ˈslækən/verb[I,T] 1 to become or make sth less tight （使）松弛: The rope slackened and he pulled his hand free. 绳子松了，他将手挣脱出来。
2 slacken (sth) (off) to become or make sth slower or less active （使）变得迟缓，减弱 · He slackened off his pace towards the end of the race. 快到赛跑终点的时候，他的脚步放慢了。