A submarine boat; esp., Nav., a submarine torpedo boat; -- called specif. submergible submarine when capable of operating at various depths and of traveling considerable distances under water, and submersible submarine when capable of being only partly submerged, i.e., so that the conning tower, etc., is still above water. The latter type and most of the former type are submerged as desired by regulating the amount of water admitted to the ballast tanks and sink on an even keel; some of the former type effect submersion while under way by means of horizontal rudders, in some cases also with admission of water to the ballast tanks.
Being, acting, or growing, under water in the sea; as, submarine navigators; submarine plants.
If you're trying to get someone who's sick with a fever off of a submarine and it's cold and raining outside, the only way in and out of a submarine, generally, is through a fairly narrow hatch. Laurel Clark
When you're on a submarine you're usually underwater for months at a time, and you don't get to Skype or make phone calls. When you get messages, they're maybe two sentences. They're very short. Jessy Schram