-biontsuff. Living organism; mode of living: halobiont.[bi(o)- + -ont.]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.-biont , a combining form meaning ?an organism? or ?a part of an organism? that takes the form or lives in the environment specified by the initial element: phycobiont. [