Definition of lustrum in US English:


nounPlural lustrums, Plural lustra

historical, literary
  • A period of five years.

    • ‘37 years ago my first secretary was a lady who has remained my friend for nearly 8 lustrums (4 decades) and today is a leading lady lawyer in Los Angeles who has never lost a case in court.’
    • ‘The book is dedicated to Nygren's wife Irmgard "in thankfulness for seven lustrums of theological cooperation."’


Late 16th century: from Latin, originally denoting a purificatory sacrifice after a quinquennial census.