English
impotable
From im- + potable.
Latin pōtus
Latin pōtō ‘drink’
Latin pōtābilis ‘drinkable, potable’
Old French potable
Middle English potable ‘drinkable, potable’
English potable
Today it means
adj not drinkable
Language periods are conventional ranges, not dates for this word.
Etymograph / impotable