1. if a liquid — especially water, milk, or a hot drink — is undrinkable, it is so
1.adjectiveB2
Definition
if a liquid — especially water, milk, or a hot drink — is undrinkable, it is so dirty, contaminated, or badly made that you cannot or should not drink it
Example
The water from the old well was muddy and completely undrinkable.
completely + undrinkable for total unsuitability
After the flood, the tap water became undrinkable for nearly a week.
became + undrinkable for [time period]
Salma poured the undrinkable coffee down the sink and made a fresh pot.
The tea sat on the counter so long that it turned cold and undrinkable.
turn + undrinkable describing a change in condition
Without a proper filter, the river water was undrinkable because of the mud and bacteria.
All four describe liquids you would rather not drink, but they differ in why. 'undrinkable' is the broadest: it covers any reason — safety, taste, temperature, or staleness — and is the most common everyday word. 'contaminated' is more specific and alarming: it means the liquid has been polluted with harmful substances (bacteria, chemicals, sewage) and is dangerous. 'unpalatable' is formal and focuses purely on the taste being unpleasant, regardless of safety. 'stale' is narrower still, describing liquid or food that has lost its freshness from age (stale beer, stale water). In conversation, if a friend offers you water from a mountain stream, you would say 'Is it drinkable?', not 'Is it potable?' or 'Is it unpalatable?'
Old English (drincan)Latin (-abilis via French)English
Formed by adding the prefix 'un-' (meaning 'not') to the adjective 'drinkable', which itself combines the Old English verb 'drincan' (to drink) with the suffix '-able' (from Latin '-abilis', via French, meaning 'capable of being'). The word has been used since the early 1600s to describe liquids that are not fit to drink.