bashrc の "rc" が何を意味するのかについての答えを見かけたので備忘として残しておきます。
マサチューセッツ工科大学（Massachusetts Institute of Technology）の略称。
CTSS（Compatible Time-Sharing System、互換タイムシェアリングシステム）は、MIT計算センターで開発された世界初のタイムシェアリングシステムのひとつ。
タイムシェアリングシステム (Time Sharing System, TSS) は、1台のコンピュータを複数のユーザが同時に利用するためのシステムのこと。
Question：VIMRC, SCREENRC, BASHRC, KSHRC, etc. What does the “RC” mean? In these and other applications what does the "RC" stand for?
Answer 1：There's a bit of interesting historical perspective about its derivation on this page:
"rc" derives from "runcom", from the MIT CTSS system, ca. 1965.
"rc" in Unix is a fossil from that usage.'
Answer 2：It stands for Run Commands. And as the name already says it can contain a listing of commands to run. For example in a xinitrc file You can list commands to run when initializing X. so you can make a Xterm window popup, or load GDM/Gnome.
In the context of Unix-like systems, the term rc stands for the phrase "run commands". It is used for any file that contains startup information for a command. It is believed to have originated sometime in 1965 at a runcom facility from the MIT Compatible Time-Sharing System (CTSS).
From Brian Kernighan and Dennis Ritchie:
There was a facility that would execute a bunch of commands stored in a file; it was called runcom for "run commands", and the file began to be called "a runcom". rc in Unix is a fossil from that usage.
Tom Van Vleck, a Multics engineer, has also reminisced about the extension rc: "The idea of having the command processing shell be an ordinary slave program came from the Multics design, and a predecessor program on CTSS by Louis Pouzin called RUNCOM, the source of the '.rc' suffix on some Unix configuration files."
This is also the origin of the name of the Plan 9 from Bell Labs shell by Tom Duff, the rc shell. It is called "rc" because the main job of a shell is to "run commands".
While not historically precise, rc may also be expanded 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. In The Art of Unix Programming, Eric S. Raymond consistently refers to rc files as "run-control" files.