TS : Underwater Casing / Housing, , usually we refer to those hard plastic or metal casing, complete with o ring to form the seal. And there are buttons on the casing / housing.
I wouldn't say waterproof, as a single grain of sand, salt crystal, too much lub on the o ring or even an out of shape o ring can , and had ,caused drownings of cameras.
If you are not intending to dive with the camera, i suggest a $1 large ziplock bag from the army market at lavender will serve the purpose of waterproofing the camera during a heavy downpour. Use 2 ziplocks, with the sealed opening facing opposite direction will be more than enough. Since this is the way we waterproof our contents in our fieldpack when we do river crossing during army days. Nothing got wet.
if u need to know how a underwater plastic / metal housing / casing look like,
just google for ikelite, nexus housing. There are alot of other brands too.