Binding v. is the act of resolving a name to a value in some scope.
A Binding n. is a record of such a resolution. The cmdName Tcl_Obj is a Binding.
Tcl has several different ways to bind names which are canvassed in scope.
Binding is of course also the act of associating, with the bind command (or the bind subcommand of a canvas), a Tk event with a bindtag and a script (most often a single command).