TIGHTEN UP Antonyms There are 4 antonyms of the phrase tighten up. (opposite meanings)Did you mean?Definition of TIGHTEN UPSynonyms of TIGHTEN UPAlso try opposite words for..tighttightertightenedtighteningBest Opposite Words For TIGHTEN UPTop 20Top 10 Top 20 (Default)Top 50 Top 100 All All (Default)WordsPhrases All All (Default)Verb Noun Adjective Adverb RankWordSave?Synonyms..UsageType1loosenverbv2relaxverbv3slackenverbv4loosen upverbv Alternatives for LOOSEN Words (13)relaxundoreleaseunfastenuntieslackenunbindunlooseunlatcheaseliberatelooseteasePhrases (4)let output outset freetease apartOpposite words for loosen Alternatives for RELAX Words (9)loosenunbendunwinddecompresslooseslackslackenunlaxunstrainPhrases (4)loosen upmake relaxedslack upslow downOpposite words for relax Alternatives for SLACKEN Words (4)slackrelaxremitslowPhrases (3)slack upslow downslow upOpposite words for slacken