clin·da·my·cin (kl?n?d?-m??s?n)n. A semisynthetic antibiotic, C18H33ClN2O5S, derived from lincomycin and active against gram-positive bacteria.[Alteration and blend of chloro- and lincomycin (with d perhaps from deoxy-).]American Heritage® Dictionary of the English Language, Fifth Edition. Copyright © 2016 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.clindamycin (?kl?nd??ma?s?n) n (Medicine) an antibiotic used to treat bacterial infectionsCollins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014