o·lan·za·pine (?-l?n?z?-p?n?)n. A psychotropic drug, C17H20N4S, used to treat schizophrenia, bipolar disorder, and acute psychosis.[olan-, origin unknown + alteration of (dia)zepine, seven-member ring containing two nitrogens; see benzodiazepine.]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.