Source : Webster's Revised Unabridged Dictionary (1913)

Poteen \Po*teen"\, Potheen \Po*theen"\, n. [Ir. poitin a small
   pot, whisky made in private stills; cf. pota pot, fr. E.
   pot.]
   Whisky distilled in a small way privately or illicitly by the
   Irish peasantry.

Poteen \Po*teen"\, n. [Cf. Ir. potaim, poitim, I drink, poitin a
   small pot.]
   Whisky; especially, whisky illicitly distilled by the Irish
   peasantry. [Written also {potheen}, and {potteen}.]

Source : WordNet®

poteen
     n : unlawfully distilled Irish whiskey