Source : WordNet®

let up
     v 1: become less in amount or intensity; "The storm abated"; "The
          rain let up after a few hours" [syn: {abate}, {slack off},
           {slack}, {die away}]
     2: reduce pressure or intensity; "he eased off the gas pedal
        and the car slowed down" [syn: {ease up}, {ease off}]