What does USS stand for?

What does USS mean?

USS	United States Senate Governmental » US Government
USS	United States Senate Governmental » FBI Files
USS	United States Steel Business » Firms
USS	United States Ship Governmental » Transportation
USS	United States Ship Miscellaneous » Ship Types
USS	United States Ship Governmental » NASA
USS	Unix System Services Computing » General
USS	Universities Superannuation Scheme Academic & Science » Universities
USS	United States Swimming Community » Sports
USS	United Space Ship Miscellaneous » Unclassified
USS	United States Ships Governmental » Military
USS	Under Seat Steering Governmental » Transportation
USS	United Star Ship Miscellaneous » Science Fiction
USS	United Seamen's Service Governmental » Military
USS	Uncorrected Sum Of Squares Miscellaneous » Unclassified
USS	United Solar Systems Miscellaneous » Funnies
USS	The United States Of Saturn Miscellaneous » Funnies
USS	United States Starship Miscellaneous » Science Fiction
USS	United States Spaceship Miscellaneous » Science Fiction
USS	Unstable Steady State Academic & Science » Electronics
USS	Universal Star Ship Miscellaneous » Science Fiction
USS	Ultimate Short Shifter Governmental » Transportation
USS	Unusual Star Shape Academic & Science » Astronomy
USS	United Ship Of Stacey Miscellaneous » Unclassified
USS	User Submissions System Miscellaneous » Unclassified