unrepeatable - definition and synonyms

adjective 

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/ˌʌnrɪˈpiːtəb(ə)l/
  1. 1
    containing offensive words that you do not want to say

    an unrepeatable joke

  2. 2
    something that is unrepeatable can only be done once or not very often because it is very special

    an unrepeatable experiment/offer