sec·ond-class (s?k??nd-kl?s?)adj.1. Of secondary status: second-class issues.2. Of or relating to travel accommodations ranking next below the highest or first class.3. Considered or treated as inferior in status, rights, or privileges in comparison with some others: second-class citizens.sec?ond class? adv.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.sec?ond class? n. 1. the class of accommodations inferior to first class but superior to third class. 2. the class of mail consisting of newspapers and periodicals not sealed against postal inspection. sec?ond-class? adj. 1. of a secondary class or quality. 2. second-rate. 3. deprived of certain civil rights: second-class citizens. [1830?40] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.