Added 10 October 2026 tranquilliser noun Categories: ThingsObscure Words noun ! Definition from WordNet 3.1, Princeton University. More about tranquilliser at Wordnik → Where our words come from → A drug used to reduce stress or tension without reducing mental clarity. Related Words: tranquilizersedativeanestheticpainkillerpilldownertranqquietivetranxcalmantrelaxativecalmative Back to today's word