“rc” in .bashrc stand for:

• It stands for “run commands”.
• This comes from MIT’s CTSS (Compatible Time-Sharing System) and Multics, where the idea that a command processing shell would be an ordinary program originated.
• CTSS had a program called RUNCOM (for “run commands”) and a script was called “a runcom” in the community where Unix originated, leading to the file extension .rc and generally to the rc abbreviation.
• rc stuck as a name for any list of commands.

1.run commands
2.resource control
3.run control
4.runtime configuration

In run control, ESR says so.

His footnote says:

• The ‘rc’ suffix goes back to Unix’s grandparent, CTSS.It had a command-script feature called “runcom”. Early
  Unixes used ‘rc’ for the name of the operating system’s boot script, as a tribute to CTSS runcom.
• “run commands” as the default long-form, but admits that context should determine word choice.
• While not historically precise, rc may also be pronounced as “run control”, because an rc file controls how a program runs.
• For instance, the editor Vim looks for and reads the contents of the .vimrc file to determine
  its initial configuration.
• The most sensible pronunciation depends on the function of the file: to start
  something up, or to control how something starts up.