Lifetime/ˈlaɪftaɪm/ Definition 1 of 2Pro Tip 1/3Unique Occasion Used to emphasize rare or once-in-a-lifetime events or opportunities. Meeting the president was a lifetime chance. Pro Tip 2/3Personal Journey Refers to the personal experiences or developments over an individual's life. Her autobiography captures her lifetime of adventures. Pro Tip 3/3Emotional Weight Carries emotional significance when reflecting on life's milestones or memories. His lifetime of service to the community was honored.