chlortetracycline (kl???t?tr??sa?kli?n) n (Pharmacology) an antibiotic used in treating many bacterial and rickettsial infections: obtained from the bacterium Streptomyces aureofaciens. Formula: C22H23ClN2O8Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014chlor?tet?ra?cy?cline (kl?r?t? tr??sa? kl?n, -klin, klo?r-) n. a yellow, crystalline, antibiotic powder, C22H23N2O8Cl, produced by Streptomyces aureofaciens, used in the treatment of infections. [1950?55] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.