1. not marked with or having a date

Examples

• The undated letter made it difficult to determine when it was written.
• She found an undated photograph in her grandmother’s attic.
• The museum displayed several undated artifacts from the ancient civilization.
• His undated journal entries were arranged by topic rather than chronology.
• The undated check could not be processed by the bank.
• Archaeologists discovered undated pottery shards at the excavation site.