Definify.com
Webster 1913 Edition
Fortieth
1.
Following the thirty-ninth, or preceded by thirty-nine units, things, or parts.
2.
Constituting one of forty equal parts into which anything is divided.
For′ti-eth
,Noun.
One of forty equal parts into which one whole is divided; the quotient of a unit divided by forty; one next in order after the thirty-ninth.
Webster 1828 Edition
Fortieth
FOR'TIETH
,Adj.