- derived from an Old Norse word related to fjord, this word describes an estuary or wide inlet of the sea. In historical documents it often appears in the form frith, which looks like an error to our modern eyes but is a reminder that not all forms of language (including modern Scots) are standardised. A seventeenth-century example occurs in Robert Bell's account of the Siege of the Castle of Edinburgh (1689) – witnesses reported seeing a fleet of Dutch doggers (ships) making up the Frith.
In place-names, frith sometimes refers to a wood, or a clearing in a wood, but in such cases we are dealing with a completely different word, derived from Old English. Fortunately the local topography can often help to determine which of the terms has been used.