The ordinal number matching the number 40 in a series.(noun)
One of 40 equal parts.(noun)
American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Use "fortieth" in a sentence
""This is the measure of the Truma" (or, of the oblation yielded to the priests), A good eye yieldeth one out of forty; that is, the fortieth part."
"But the feast then had no proper name; it was simply called the fortieth day after Epiphany."
"This same year, that is to say the fortieth year after the passion of our"