Yesterday I learned that in emacs lisp, "defvar" is a definition that is set one time only and from that point on can never be changed (i.e. can not be VARied)

Yesterday I learned that in emacs lisp, "defvar" is a definition that is set one time only and from that point on can never be changed (i.e. can not be VARied) and "defconst" is a definition that can be changed (i.e. is not CONSTant). Naming things is hard.