(extracts from 'The Origin and History of Irish Names of Places' by P.W. Joyce. Published by Appletree Press)

Poll: a hole of any kind. Topographically it is applied to holes, pits or caverns in the earth, deep small pools of water, very deep spots in rivers or lakes, etc. In the beginning of anglicised names it is always made Poll, Poul, or Pull, and as a termination it is commonly changed to Foyle, phuill, phull by aspiration of the 'P', and by the genitive inflexion. Diminutives: Pullen, Polaun, Polleens, Pollagh, Pullagh.

There are several words for a cave: poll, poll-talmhan (poultaloon), dearc (derrig) or derc (a cave or grotto), cuas (anglicisations: Coos, Coose, Cose, Cous, Couse). Sometimes the 'C', is changed to 'H', e.g. Hoosh. Diminutives: Coosan, Coosane, Coosaun, Coosheen. In addition: Uagh, Uaimh (genitive: Uamha, Uamhain) and Uath are very common, the latter denoting an occurrence in a cave. Anglicisations: Nahoe, Nahoo, Nahoova, Nahone, Nahoon, Oovan, Owen (occasionally).

Indications of water are numerous: Uisce, anglicised to Iska, Isky, and Isk. Turlough: dried lake. Tobar, Tiobrad: well (Tober, Tipper, Tubber, Tubbrid). Uaran, Fuaran: fresh or cold water springing from the earth (Oran).