invariable - not liable to or capable of change; "an invariable temperature"; "an invariable rule"; "his invariable courtesy"

same - closely similar or comparable in kind or quality or quantity or degree; "curtains the same color as the walls"; "two girls of the same age"; "mother and son have the same blue eyes"; "animals of the same species"; "the same rules as before"; "two boxes having the same dimensions"; "the same day next year"