USS is a three-letter acronym, or 'TLA' that may designate one of the following:

• United States Ship Typically as a ship prefix in the United States Navy
• United Star Ship (Star Trek)
• United States Standard, an older standard of screw thread
• Uncorrected sum of squares
• Under-seat steering
• Uniform Symbology Specification
• Union syndicale suisse (uss.ch)
• United States Senate
• United States Steel Corporation
• Universities Superannuation Scheme (UK)
• UNIX System Services
• USA Swimming
• User Support Services (several)