Be careful when people say Metamidion, I've heard people say metamidion and seen the pyramidion equipped as a carronade flamer.... Not a metamidion...
The goio.vocab is huge for the known community, and most of commonly used terms are here...
However I've heard so many people use almost a different language (no not the Russians, Polish or Germans....) but Americans and English who seriously, have just made up their own words for things in the game because they're unaware of the existing community and languages used....
(Almost like the ducks, except only the person talking knew what he meant.)
A few examples of random made up stuff I've seen:
Gatling gun: "Heavy" because "Its a TF2 reference innit, cause its like the heavy's gun." How dare Sasha be compared to a rusty mounted gun!
Mortar: "Nade gun." Because its almost like a grenade launcher... Mortar is easier to bark out imo...
Flamer: "The hot one" every time... "Enemy will be on our left side, man the hot gun!"
All hwacha galleon: "more-ticores" a dude who genuinely thought a quad hwacha galleon should be called more-ticores"
Some me and my friends use but are often debated as having other names/meanings
Man the aft guns: "shoot.a.flare!"
To your positions: "Man the aft guns!"
Nah I'm gunna buff flare gun: "I'm getting on aft guns!"
Hwacha fish: "Catfish"
Ship with out a chance: "Flakfish"