The orlop deck is the lowest deck in a ship (except for very old ships). It is the deck or part of a deck where the cables are stowed, usually below the water line. It has been suggested the name originates from "overlooping" of the cables.

It has also been suggested that the name is a corruption of "overlap," referring to an overlapping, balcony-like half deck occupying a portion of the ship's lowest deck space. According to the Oxford English Dictionary, the word descends from Dutch overloop from the verb overloopen (English: to walk over) via Middle English.