slack·en 
/ˈslækən/ verb
slack·ens; slack·ened; slack·en·ing /ˈslækən/ verb 1 a [no obj] : to become slower or less active : to slow down
▪ Sales show no sign of slackening. ▪ The wind slackened (off) and the sky cleared.
b [+ obj] : to make (something) slower or less active
▪ She slackened her speed/pace [=she slowed down] after she slipped on the ice. 2 : to become less tight or to make (something) less tight : loosen [no obj] ▪ As he began to relax, his grip on the steering wheel slackened. [+ obj] ▪ He slackened his grip. ▪ The captain ordered us to slacken the sails.
▪ Sales show no sign of slackening. ▪ The wind slackened (off) and the sky cleared.
b [+ obj] : to make (something) slower or less active
▪ She slackened her speed/pace [=she slowed down] after she slipped on the ice.
