thoughtfulness n. + Add to list US //ˈθɔtfəɫnɪs// UK //θˈɔːtfəlnəs// thought·ful·ness SynonymsAntonymsEtymology Synonyms consideratenessconsiderationcontemplationmusingreflectionrumination Antonyms inconsiderationthoughtlessnessunthoughtfulnessOrigin From thoughtful + -ness.