Take the 2-minute tour ×  In the Star Trek normal universe,
almost all of Starfleet's starships were named with the prefix
USS: Count from list. Some popular ones: USS Enterprise -
series, USS Stargazer, USS Exeter, USS Defiant, USS Excelsior,
USS Voyager, USS Titan, USS Reliant, USS Equinox, USS Grissom,
USS Relativity, etc.  In the mirror universe, Starfleet's
starships were named with the prefix ISS. We don't have a big
list, but we do see these: ISS Enterprise NX-01, ISS Enterprise
NCC-1701, ISS Avenger.  What's the full form of USS & ISS in
Star Trek canon?  In the real world, the US Navy uses USS in
ship names, which is reasonable as "United States Ship", but why
is it used in Star Trek canon (in which there's no US to control
starships)?  In the mirror universe, USS is replaced with ISS.
Why? Does ISS have a meaning opposite from that of USS?
share|improve this question  4 Answers 4  up vote 17 down vote
accepted  USS has had several meanings.  From an article on
TheGeekTwins exploring the same questi