Gahan is a surname

Surname

A surname is a name added to a given name and is part of a personal name. In many cases, a surname is a family name. Many dictionaries define "surname" as a synonym of "family name"...

 with several different origins. One origin of the surname is from a reduced form of McGahan

McGahan (surname)

MacGahan, and McGahan, are of Northern Irish surnames. They are Anglicised forms of the Irish language Mac Eacháin, meaning "son of Eachán"...

, which is in turn an Anglicised form of the Irish language

Irish language

Irish , also known as Irish Gaelic, is a Goidelic language of the Indo-European language family, originating in Ireland and historically spoken by the Irish people. Irish is now spoken as a first language by a minority of Irish people, as well as being a second language of a larger proportion of...

 Mac Eacháin

Mac Eacháin (surname)

Mac Eacháin is an Irish language surname. It is the patronymic form of the personal name Eachán. The personal name Eachán is diminutive of the personal name Eachaidh, which is derived from each, meaning "horse". Anglicised forms of the surname include: Gahan; McCaughan; MacGaffin, and McGaffin;...

, meaning "son of Eachán". Another origin of the name, in Leinster

Leinster

Leinster is one of the Provinces of Ireland situated in the east of Ireland. It comprises the ancient Kingdoms of Mide, Osraige and Leinster. Following the Norman invasion of Ireland, the historic fifths of Leinster and Mide gradually merged, mainly due to the impact of the Pale, which straddled...

, is from a reduced form of the Irish language Ó Gaoithin, meaning "descendant of Gaoithín". The personal name

Personal name

A personal name is the proper name identifying an individual person, and today usually comprises a given name bestowed at birth or at a young age plus a surname. It is nearly universal for a human to have a name; except in rare cases, for example feral children growing up in isolation, or infants...

 Gaoithín is a diminutive

Diminutive

In language structure, a diminutive, or diminutive form , is a formation of a word used to convey a slight degree of the root meaning, smallness of the object or quality named, encapsulation, intimacy, or endearment...

 of gaoth, meaning "wise", or "wind". In Connacht

Connacht

Connacht , formerly anglicised as Connaught, is one of the Provinces of Ireland situated in the west of Ireland. In Ancient Ireland, it was one of the fifths ruled by a "king of over-kings" . Following the Norman invasion of Ireland, the ancient kingdoms were shired into a number of counties for...

, Ó Gaoithin is sometimes Anglicised as Wynne or Wyndham. Occasionally, the surname Gahan may be an Anglicised form of the Irish language Mac Gaoithín, meaning "son of Gaoithín", although the more common Anglicised form of this Gaelic name is McGeehan in Ulster

Ulster

Ulster is one of the four provinces of Ireland, located in the north of the island. In ancient Ireland, it was one of the fifths ruled by a "king of over-kings" . Following the Norman invasion of Ireland, the ancient kingdoms were shired into a number of counties for administrative and judicial...

.