Added 9 October 2026 thoughtlessness /ˈθɔːtləsnɪs/ noun Categories: Describing WordsRare Words In Latin: temeritās Wiktionary noun ! Definition from WordNet 3.1, Princeton University. Pronunciation from Wiktionary, via Kaikki.org. More about thoughtlessness at Wordnik → Where our words come from → The quality of failing to be considerate of others. The trait of not thinking carefully before acting. Related Words: inconsiderationinconsideratenessunthoughtfulnessindifferenceinconsistencyfollylevitylightnessnoncaringuncaringinsoucianceregardlessness Back to today's word