Availability and grammar shape Royal Navy ship names

Why does the Royal Navy use names such as Defiance and Reliance rather than Defiant and Reliant?

Because the noun forms better fit Royal Navy naming practice, while prestigious names also cannot be reused until they are available.

A celebrated name is available to a new battleship only when no serving ship already bears it. The Royal Navy would not normally rename an older hull merely to move Warspite into a newer class. The following question asks why the service lacks Defiant or Reliant and points instead to the established noun forms Defiance and Reliance. Those forms fit British naming phraseology better than the corresponding adjectives. Continuity, availability, and grammatical taste all shape the name pool.