For the novel by Steve Alten, see The Loch A loch (usually Lough as a name element outside Scotland) is a body of water which is either: a lake or; a sea inlet, which may be also a firth, fjord, estuary or bay. Sea-inlet lochs are often called sea lochs. Background This name for a body of water is Gaelic in origin and is applied to most lakes in Scotland and to many sea inlets in the west and north of Scotland. For a list, see List of lochs in Scotland. As a name element Loch has become Lough… (More on Loch)