Synonyms that are in the dictionary are marked in green. Synonyms that are not in the dictionary are marked in red.
Antonyms that are in the dictionary are marked in green. Antonyms that are not in the dictionary are marked in red.
The acronym, which stands for eXplore, eXpand, eXploit, and eXterminate, was first postulated during a game review from Computer Gaming World.