Noun

(en noun)

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

*{{quote-magazine, year=2013, month=September-October, author=(Henry Petroski)

, magazine=(American Scientist), title= The Evolution of Eyeglasses , passage=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 .}}

Any object for this purpose.

John used his coffee mug as a paperweight.

(slang) An otherwise useless piece of equipment.