Adjective undated has 1 sense

1. dateless, undated - not bearing a date; "a dateless letter"
   Antonyms: datable, dateable (indirect, via undatable)
   

Undated

Part of speech: Adjective, Verb

Sense 1 (Adjective): Not having a specific date

Usage: This undated letter is causing confusion as we cannot determine when it was written.

Related products: Undated calendar, Undated planner

Sense 2 (Verb): To not write or assign a specific date

Usage: The professor decided to undate the assignment submission to provide some flexibility to the students.

Related products: Undated notebook, Undated journal