submersible noun 5adjective 1forms 1 noun5 •A small nonmilitary, nonnuclear submarine for exploration. •(US) A very small baby submarine designed for specific localized missions, usually while tethered to a submarine or ship for life support and communications. •An underwater vehicle with limited mobility, similar to a submarine, but less mobile. •(UK) A retroactive term used for nonnuclear submarines; nuclear submarines are termed true submarines. •(UK) A term used primarily by some navies for nuclear submarines, termed true submersibles, because they cannot retroactively declare that their nonnuclear submarines should be called by a different name. adjective1 •Able to be submerged. formssubmersibles