も同然 => just like; same as ~ N2
全然~ない => (not) at all N4
いぜん (依然) => still, as yet, as it has been N3
Invariant
~もどうぜんだ(~も同然だ)      => just like; same as ~ N1
当然だ/当たり前だ => natural; as a matter of course N2
も[同然「どうぜん」]だ => The same as saying A, as good as A N2
Adjectival, Descriptions