Carhoo firstly appears c. 1590 as 'Carown' in a sketch map The description of Muskery, retained as part of the Dartmouth Map Collection, at the National Maritime Museum, Greenwich.

[1] In the Down Survey Maps (1656-8), it is referred to as 'Carrow' [2] and 'Carrooe', and the accompanying terrier lists Thomas and Edmund Coppinger as proprietors by way of mortgage.

[3] The Ordnance Survey name book (c. 1840) describes Carhoo Upper as bounded on the north by Rockgrove townland and on the west by Aghinagh parish.

O'Murchú (1991) holds Ceathrú as meaning a quarter, in this instance a measurement of land, such as a townland or ploughland, and being a smaller division than a tuath or triocha céad.

[4] The Placenames Database of Ireland gives the townland an Irish name of An Cheathrú Uachtarach, with Ceathrú meaning a quarterland.