NAMEbuiltin - Execute the specified shell builtin, passing it arguments, and return its exit status
builtin shell-builtin [arguments]
Execute the specified shell builtin, passing it arguments, and return its exit status. This is useful when defining a function whose name is the same as a shell builtin, retaining the functionality of the builtin within the function. The cd builtin is commonly redefined this way. The return status is false if shell-builtin is not a shell builtin command.
This is extracted from the main bash man page, see there for more details.