#millennium  a span of 1000 years
  supertype:  time_period__period__period_of_time  an amount of time; "a time period of 30 years"; "hastened the period of his recovery"
  part:  century  100 years
     part:  decade__decennary__decennium  a period of 10 years
        part:  twelvemonth__yr  a period of time containing 365 (or 366) days; "she is 4 years old"
     part:  half-century  50 years
     part:  quarter-century__quartercentury  25 years

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