Dublin enjoys dozens of colloquial terms for neighborhoods and areas in the city, many of whom have now been assimilated into everyday language.
I’ve tried to compile a list of ones that I can think of. Others may be more ‘true’ than others. Have I forgotten any?
Colloquial areas:
Perrystown, “a small south Dublin suburb located between Terenure, Greenhills, Templeogue and Crumlin” which was probably named after a former family of landowners in the area, the Perrys. While technically not an “unofficial area”. It would probably be better described as a small suburb within a larger one? Wikipedia says it is known as “The Secret Suburb” by its residents.
Cowtown, an area in Dublin 7 beside Stoneybatter where there was once sprawling cattle markets. Street names like Oxo, Nialler, Murtagh, Beneeder, the Norrier leave a reminder of the area’s past.

Informal group of Bohs supporters who live or grew up in the area.
Maryland, a name for a small area just off Cork St.
Broadstone, an area of the North inner city bounded roughly by Phibsborough Road and Constitution Hill to the West, North Circular Road to the north, and Dorset Street and Bolton Street to the south-east.
Harmonstown, is a small suburban locality straddling the boundary between modern-day Artane and Raheny. The locality is bounded by the railway cutting, the Springdale Road Linear Park and Brookwood Avenue. It also borders Killester and Clontarf.
Summerhill, an area of the North Inner City. Anyone suggest what area actually constitutes Summerhill i.e. what boundries etc.?
Historical areas that have dissapeared or have changed their name:
Hell, a popular term in the 17th century for the area around Christ Church Yard.

A description of ‘Hell’ from The Irish Times (10 Mar 1923)
The Monto, nickname for a one-time notorious red light district bounded by Talbot Street, Amiens Street, Gardiner Street and Seán McDermott Street (formerly Gloucester Street).
Mud Island/Friend’s Field/French Field, previous names for Ballybough.
Doyle’s Town, previous name for Baldoyle.
Annadale, previous name for Fairview
Ballyboother, previous name for Booterstown.
Scald Hill, previous name for Sandymount
Cullenswood, a previous name for the area around Ranelagh and Rathmines
Nicknames:
Raytown is a nickname for Ringsend, reflecting its history as a fishing village.

The Blades’ 1985 singles compilation, ‘Raytown Revisted’. The band all grew up in the area.
Nine Arches, previous nick name for the area around Milltown