Northern Ireland's second-largest city has two names in daily use
Its legal name, set by royal charter in 1613, is Londonderry. Its older name — the one most residents actually say — is Derry. Neither has fully replaced the other, four centuries later.
Londonderry
Granted by royal charter in 1613, when King James I awarded the walled city to London trading guilds that funded its construction. It remains the city's official legal name today.
Derry
From the Irish "Doire" ("oak grove"), the name in use for centuries before the 1613 charter. Most residents use this name day to day, and it's the name the local council itself uses.
Even the city's own government is split on paper. The local authority is legally named "Derry City and Strabane District Council," while the city it governs remains officially "Londonderry" by charter — a 2007 push to formally rename the city itself stalled without resolution. Neutral sources like the BBC often write "Derry~Londonderry" or "(London)Derry" to sidestep picking a side; road signage varies by which community maintains a given stretch of road.
Sources: Royal Charter of 1613; Derry City and Strabane District Council official name; BBC style guidance on Northern Ireland place names.