From Longman Dictionary of Contemporary EnglishKlaxonKlax‧on /ˈklæksən/ noun [countable] trademark TTCa loud horn used on police cars and other official vehicles in the past
Examples from the Corpus
Klaxon• A Klaxon sounded from the Regatta and we were soon triumphantly on our way home again.Origin klaxon (1900-2000) Klaxon, a trademark 