Delaney is originally a
Norman French surname based on the French phrase
del aunie, "from the alder grove." This
Norman French surname became an Irish surname when it was used to Anglicize the Gaelic family name
O Duibhslaine. In terms of surnames,
Delaney is therefore BOTH a
Norman French and English surname, and an Irish surname.
There are many other Irish surnames which have similar histories to
Delaney, where a
Norman French or English name was used to "Anglicize" a Gaelic name, and so there are a great many names which have separate but equally legitimate derivations as both English and Irish family names. A few others that start with D and that are found in Hanks & Hodges's
A Dictionary of Surnames include
Darby,
Darcy,
Dennis,
Denny,
Dillon, Diver, Dockray, Dodd,
Doran, Dore, Dormer, Dove, Drane,
Drew, Dunn, and Dyer.