1. a period of five years
Usage: formal; literary
2. in ancient Rome, a purification ceremony held every five years after the census
Usage: historical; Roman antiquity

Examples

• The company’s strategic plan covers the next lustrum.
• Economic growth over the past lustrum has been steady.
• The Roman lustrum involved sacrificial offerings to the gods.
• Census data was collected at the end of each lustrum.
• The poet reflected on changes during the recent lustrum.
• Ancient Romans marked each lustrum with elaborate ceremonies.