submersible

UK A small nonmilitary, nonnuclear submarine for exploration.

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.

US A very small baby submarine designed for specific localized missions, usually while tethered to a submarine or ship for life support and communications.

Nautical, Transport An underwater vehicle with limited mobility, similar to a submarine, but less mobile.