In early use: a type of French red wine. Later: specifically a dark red wine similar to port, produced mainly in South Africa; (also) the distinctive red-fleshed variety of grape from which this wine is made.
In early use the word may have referred to the sort of wines produced by the Pontac family in the Bordeaux region of France.
Late 17th century; earliest use found in Thomas Blount (1618–1679), antiquary and lexicographer. Apparently from French Pontac (although this is not attested in dictionaries of French until later), further etymology uncertain: perhaps from de Pontac, the name of an influential French wine-making family.