If those are the most prominent things you find for that abbreviation, I have to start doubting Wikipedia. As a German seeing that abbreviation so freely used is always a little bit shocking.
They aren't. I think that's the point. If you type "SS" into Wikipedia you get straight to Schutzstaffel. It's hard to find what it means in the context of ships.
In all fairness, the term is much older than what that acronym's come to mean.
I always thought it stood for "Set Sail", but this definition is more pragmatic.
I assume the problem was that prominence of certain German use makes finding other meaning of this phrase tricky.
Wait until you learn about SS the government security service. https://en.wikipedia.org/wiki/United_States_Secret_Service
(Officially USSS, but it's often abbreviated to SS in common parlance.)
The German one isn't relevant for post-war American ships. Hope that helps.