Definition of lessen verb from the Oxford Advanced American Dictionary

      

    lessen

     verb
    verb
    NAmE//ˈlɛsn//
     
    [intransitive, transitive]Verb Forms present simple I / you / we / they lessen
     
    he / she / it lessens
     
    past simple lessened
     
    -ing form lessening
     
     
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  1. 1to become or make something become smaller, weaker, less important, etc. synonym diminish
  2. 2 The noise began to lessen. lessen something to lessen the risk/impact/effect of something They gave her an injection to lessen the pain.
 
noun [singular, uncountable] a lessening of tension
See the Oxford Advanced Learner's Dictionary entry: lessen