bac·te·ri·o·stat (b?k-tîr??-?-st?t?)n. An agent, such as a chemical or biological material, that inhibits bacterial growth.bac·te?ri·o·stat?ic adj.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.