Loch (/lɒx/) is the Scottish Gaelic, Scots and Irish word for a lake or sea inlet. It is cognate with the Manx lough, Cornish logh, and one of the Welsh words for lake, llwch.
In English English and Hiberno-English, the anglicised spelling lough is commonly found in place names; in Lowland Scots and Scottish English, the spelling "loch" is always used. Many loughs are connected to stories of lake-bursts, signifying their mythical origin.
Sea-inlet lochs are often called sea lochs or sea loughs. Some such bodies of water could also be called firths, fjords, estuaries, straits or bays.