Identification: river Add, Argyll
Longus is a place-name transferred to a river. The Epidi tribe appear to have used the hill-letter n2, this being seen in the old-style nd element (meaning ‘hill summit’) in Lemandonius (Lemannonius in Ptolemy), the Clauchlands hillfort high above Lamlash bay on Arran. At some time after 120BC the Epidi appear to have expanded north and west and to have founded a new settlement at Dunadd. This new settlement will have had a name such as Denconion, where Denc is an inversion-type element meaning ‘summit of hill steep’. At a later date that settlement was taken over by the Caledoni, who used the hill-letter l1. The name of the settlement was now Lodenconion. This form, with loss or omission of de, the common c→g change and modification of the ending, became Longus. This modified place-name was then transferred to the river now called the Add.
[NB. Detailed information as to the different hill-letters is given in Chapter 1 and information as to how the hill-letters were combined to form compound place-names is given in Chapter 2]