An Etymological Dictionary of Astronomy and Astrophysics

A hypothetical particle that carries a single → magnetic pole, in contrast to magnets which are north-south pole pairs.
These massive particles (billions of times heavier than the → proton) are required by grand unified theories(→ GUTs) to explain the actual matter content of the Universe, particularly the dominance of matter upon → antimatter. However, their existence contradicts → Gauss’s law for magnetism.

See also: → magnetic; → monopole.