"drinkable, suitable for drinking," early 15c., from Old French potable (14c.) and directly from Late Latin potabilis "drinkable," from Latin potare "to drink" (from PIE root *po(i)- "to drink").

"undrinkable," c.1600, from assimilated form of in- (1) "not" + potable, or else from Late Latin impotabilis.

*pō(i)-, Proto-Indo-European root meaning "to drink."

It forms all or part of: beer; bever; beverage; bib; bibitory; bibulous; hibachi; imbibe; imbrue; pinocytosis; pirogi; poison; potable; potation; potion; symposium.

It is the hypothetical source of/evidence for its existence is provided by: Sanskrit pati "drinks," panam "beverage;" Greek pinein "to drink," poton "that which one drinks," potos "drinking bout;" Latin potare "to drink," potio "a potion, a drinking," also "poisonous draught, magic potion;" Old Church Slavonic piti "to drink," pivo "beverage."