aer·obe (âr??b?)n. An organism, such as a bacterium, requiring free oxygen to live.[French aérobie : Greek ??r, air; see aero- + Greek bios, life; see gwei- in Indo-European roots.]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.aerobe (???r??b) or aerobiumn, pl -obes or -obia (-???b??) (Microbiology) an organism that requires oxygen for respiration. Compare anaerobe[C19: from aero- + Greek bios life. Compare microbe]Collins English Dictionary ? Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014aer?obe (???r o?b) n. an organism, esp. a bacterium, that requires air or free oxygen to sustain life. [1875?80; aer- + (micr) obe] Random House Kernerman Webster’s College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.