To render slack; to make less tense or firm; as, to slack a rope; to slacken a bandage.
To cause to become less eager; to repress; to make slow or less rapid; to retard; as, to slacken pursuit; to slacken industry.
To cause to become less intense; to mitigate; to abate; to ease.
become slow or slower; "Production slowed"
make less active or fast; "He slackened his pace as he got tired"; "Don't relax your efforts now"
make slack as by lessening tension or firmness