Enigmatic, Enigmatical, a.
Etymology: [Cf. F. énigmatique.]
Relating to or resembling an enigma; not easily explained or accounted for; darkly expressed; obscure; puzzling; as, an enigmatical answer.
Shades of meaning
Fernald has no entry of its own for enigmatic; he lists it under equivocal.
He lists it without comment; the entries above explain its neighbors.