-below). Here is the list: @samp{first} for 1, @samp{next} for 2,
-@samp{third} for 3, @samp{fourth} for 4, @samp{fifth} for 5,
+below). Among the most commonly used ordinal numbers, the word
+@samp{last} stands for @math{-1}, @samp{this} stands for 0, and
+@samp{first} and @samp{next} both stand for 1. Because the word
+@samp{second} stands for the unit of time there is no way to write the
+ordinal number 2, but for convenience @samp{third} stands for 3,
+@samp{fourth} for 4, @samp{fifth} for 5,