Cunniff, also spelt Cunneffe, Coniffe etc., is the most usual anglicized form of the Irish surname Mac Conduibh (cu: hound; dubh: black) and belongs almost exclusively to Counties Galway and Mayo.

Another form of the same name, MacNiff or MacNeeve is similarly associated with the adjacent Co.

Leitrim and when Strafford's Inquisition of Co. Mayo was made in 1636 MacEniffe with MacNuff appear in that county; a few years later MacConniffe and MacCunniffe were among the Irish Papist transplantees in Counties Galway and Mayo. MacAniff and MacEniffe and their spelling variants, however, are now found chiefly in Cos. Cavan and Tyrone, where Cadoo, Caddow and MacAdo or MacAdoo are also found; and these, strange as it seems at first sight, are also anglicized forms of Mac Conduibh. It would be hard to find any Gaelic Irish surname with more different anglicized forms: in addition to those mentioned above there are many rate forms occasionally found e.g. MacKiniff, MacEndoo, Caddy and Quinniff, numbering 22 in all. In the form Cadie and Caddy it occurs in the 1659 “census” (Co. Monaghan) and in the Jacobite attainders of the next generation (Navan), and in Co.

Cavan wills of a century later. In a manuscript in the National Library (G. 841) Risteárd Ó Foghlú suggests an alternative basic form for MacNeeve, MacAniff etc. viz Mac Naoimh; but I think we may accept Mac Conduibh as given by Woulfe in both cases. Another possibility is that Caddy is not a variant of Caddo but is MacCady (gaelice Mac Ada), or even perhaps the English name Cady.

In this connexion reference must be made to the Co. Cork name Canniff or Canniffe, which Woulfe says is rare though in 1852 Griffith found as many as 25 Canniffe families in west Cork. Woulfe gives 'Ó Ceannduibh for Canniff',treating it as entirely different from MacAniff. The fact that MacAniff belongs almost Canniff. exclusively to Co. Leitrim and the adjacents parts of Cavan supports its differentiation from

(Irish) The son of Cu-dubh (black hound).