English

Definition of flatline verb from the Oxford Advanced Learner's Dictionary

     

    flatline

     verb
    verb
    BrE BrE//ˈflætlaɪn//
     
    ; NAmE NAmE//ˈflætlaɪn//
     
    (informal)Verb Forms present simple I / you / we / they flatline
    BrE BrE//ˈflætlaɪn//
     
    ; NAmE NAmE//ˈflætlaɪn//
     
    he / she / it flatlines
    BrE BrE//ˈflætlaɪnz//
     
    ; NAmE NAmE//ˈflætlaɪnz//
     
    past simple flatlined
    BrE BrE//ˈflætlaɪnd//
     
    ; NAmE NAmE//ˈflætlaɪnd//
     
    past participle flatlined
    BrE BrE//ˈflætlaɪnd//
     
    ; NAmE NAmE//ˈflætlaɪnd//
     
    -ing form flatlining
    BrE BrE//ˈflætlaɪnɪŋ//
     
    ; NAmE NAmE//ˈflætlaɪnɪŋ//
     
     
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  1. 1[intransitive] to die
  2. 2[intransitive] to be at a low level and fail to improve or increase He said the party had been ‘flatlining’—failing to increase its level of support—for eight years.
  3. Word Origin 1980s: from flat ‘level’ + line (with reference to the continuous straight line displayed on a heart monitor, indicating death).
See the Oxford Advanced American Dictionary entry: flatline