simple past tense and past participle of unclassify
"The agency decided to unclassify the documents after reviewing them, even though they initially refused to do so."
In plain English: To unclassify something means to remove it from its secret status so that anyone can see what is inside.
"The government decided to unclassify the report after years of secrecy kept it hidden from the public."
not subject to a security classification
"The declassified documents were marked unclassified before being made available to the public."
not arranged in any specific grouping
"The librarian placed the unclassified books on a random shelf rather than organizing them by genre."
Not classified
"The unclassified document was placed on the public bulletin board for anyone to read."
The word unclassified is formed by adding the prefix un- to classified. It entered English as a straightforward negation of the past participle of classify, meaning "not having been categorized or assigned to a specific group."