Although Lord Kelvin first defined the word “chiral” in 1893−1894, references in the literature give dates varying from 1884 to 1904. He referred previously to hetero and homocheiral in 1873 in a note that is now lost. Apparently overlooked have been his definitions of hetero and homochiral in a text that he coauthored in 1879. The etymology of these and other related neologisms is considered. Chirality 2010. © 2009 Wiley-Liss, Inc.