paperweight

noun

1. A small, decorative, somewhat weighty object placed on one or more pieces of paper to keep them from fluttering away.

   “The ability of a segment of a glass sphere to magnify whatever is placed before it was known around the year 1000, when the spherical segment was called a reading stone, essentially what today we might term a frameless magnifying glass or plain glass paperweight.”

2. Any object used for this purpose.

   “John used his coffee mug as a paperweight.”

3. (slang)A useless piece of equipment.

   “On Windows, the card has a working driver. On Linux right now, it's a paperweight.”