The word "undated" is a straightforward English formation built upon the verb "date," which entered Middle English from Old French date and ultimately from Latin data, the feminine past participle of dare meaning "to give." In Medieval Latin, the phrase data Romae ("given at Rome") was used to note the time and place a document was issued, which is the origin of our modern concept of a calendar date. By adding the native English negative prefix "un-," meaning "not," the adjective "undated" logically describes something from which this specific information of when it was given or made has been omitted.

Structure: un (not) + dated (provided with a date) - un: A prefix of Germanic origin (Old English) meaning "not," used to form negatives. - dated: The past participle of the verb "date," from Latin data (given), referring to the notation of a specific day or time.