nonillionth

no·nil·lionth

 (nō-nĭl′yənth)
n.
1. The ordinal number matching the number nonillion in a series.
2. One of nonillion equal parts.

no·nil′lionth adv. & 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.