Since nanorobots would be microscopic in
size, it would probably be necessary for very large
numbers of them to work together to perform
microscopic and macroscopic tasks. These
nanorobot swarms, both those which are incapable
of replication (as in utility fog) and those which are
capable of unconstrained replication in the natural
environment (as in grey goo and its less common
variants), are found in many science fiction stories,
such as the Borg nanoprobes in Star Trek. The word
"nanobot" (also "nanite", "nanogene", or "nanoant")
is often used to indicate this fictional context and is
an informal or even pejorative term to refer to the
engineering concept of nanorobots. The word
nanorobot is the correct technical term in the
nonfictional context of serious engineering studies.