nounA period of 100 consecutive years; often specifically a numbered period with conventional start and end dates, e.g., the twentieth century, which stretches from (strictly) 1901 through 2000, or (informally) 1900 through 1999. The first century AD was from 1 to 100.

nounA unit in ancient Roman army, originally of 100 army soldiers as part of a cohort, later of more varied sizes (but typically containing 60 to 70 or 80) soldiers or other men (guards, police, firemen), commanded by a centurion.