klaxon (n.) Look up klaxon at Dictionary.com
"loud warning horn," 1908, originally on automobiles, said to have been named for the company that sold them (The Klaxon Company; distributor for Lovell-McConnell Mfg. Co., Newark, N.J.), but probably the company was named for the horn, which bore a word likely based on Greek klazein "to roar," cognate with Latin clangere "to resound."