1968 Dart GTS

I know we are not supposed to comment on posts. But can someone post here what a NOS part is. This could be misleading to someone new to the hobby that is not aware what a NOS part is. These obviously are not.
The chrysler part number is stamped on the inside of panel if you look at the rest of the pictures. It was described as an nos 1/4 that was previously tacked on.