: a number designating the place (such as first, second, or third) occupied by an item in an ordered sequence see Table of Numbers
2
: a number assigned to an ordered set that designates both the order of its elements and its cardinal number
Example Sentences
Recent Examples on the WebInterestingly enough, Kruskal's tree theorem required non-finite mathmatics to prove, using advanced techniques such as transfinite arithmetic and ordinal numbers. Jay Bennett, Popular Mechanics, 20 Oct. 2017