EIGHTEEN Antonyms There are 2 antonyms of the word eighteen. (opposite meanings)Did you mean?Definition of EIGHTEENBest Opposite Words For EIGHTEENTop 20Top 10 Top 20 (Default)Top 50 Top 100 All All (Default)WordsPhrases All All (Default)Verb Noun Adjective Adverb RankWordSave?Synonyms..UsageType1nineteen2seventeen Alternatives for NINETEEN Words (1)nineteenAbbreviations (2)19xixOpposite words for nineteen Alternatives for SEVENTEEN Words (1)seventeenAbbreviations (2)17xviiOpposite words for seventeen