- this term for a waterfall is more frequently found in place-names than in other written contexts, though it does appear in a small number of quotations documented in the Dictionaries of the Scots Language. These include, from David Macdonald's The Mountain Heath (1838): the hoarse murmur of the stream, That fed the rapid ess.
The word derives from Gaelic eas 'waterfall', and is found in the Bridge of Ess in Aberdeenshire and the Ess of Glen Latterach in Morayshire. The Irish Gaelic form is also found in such names as the Ess-na-Larach, or 'Mare's Waterfall' in Glenarrif, County Antrim.