From Latin absinthium, from Ancient Greek ἀψίνθιον (apsinthion), ἀσπίνθιον (apsinthion). The Ancient Greek word is of uncertain origin, albeit recognized as foreign (E.R. Wharton): underlain by a pre-Greek Pelasgian word, marked by the non-Indoeuropean consonant complex νθ. May be from Persian اسپند (ispand, “wild rue”). See also Absinthe on Wikipedia.