Not physically secured; not fastened; not attached.
"The loose ladder leaned unsecured against the wall and wobbled dangerously in the wind."
In plain English: Unsecured means something is not protected by any guarantee, collateral, or safety measures that could be taken if it goes wrong.
"He lost his wallet because he left it in an unsecured pocket on the bus."
Usage: Use unsecured to describe items that are loose, detached, or lacking physical restraints like straps or locks. This term applies when an object is free-moving and could easily fall away from its intended position without being tied down.
The word unsecured is formed by adding the prefix un- to secured, meaning it was first used simply as a negative form of that adjective. It describes something that has not been made safe or fastened, traveling directly into English through this straightforward combination without any shift in core meaning.