trichloromethane [trahy-klawr-oh-meth-eyn, -klohr-] Word Origin noun Chemistry. chloroform(def 1). Origin of trichloromethane First recorded in 1910–15; tri- + chloro-2 + methane trichloromethane in Medicine trichloromethane [trī-klôr′ō-mĕth′ān′] n.Chloroform.