Full Definition of WARTHOG. : a wild African hog (Phacochoerus aethiopicus) that has large protruding tusks and in the male two pairs of rough warty excrescences on the face and that is sometimes placed in two separate species (P. aethiopicus and P. africanus). See warthog defined for English-language learners. a wild African hog (Phacochoerus aethiopicus) that has large protruding tusks and in the male two pairs of rough warty excrescences on the face and that is sometimes placed in two separate species (P. aethiopicus and P. africanus).