These animals are at least ordinally distinct from us in those grades of groups in which naturalists arrange animals.
The relation-number of a relation is the class whose members are all those relations which are ordinally similar to it.
Also, two relations need not be serial in order to be ordinally similar; but if one is serial, so is the other.
early 14c., "book setting forth the order of services in the Church," from Late Latin adjective ordinalis (see ordinal (adj.)).
late 14c., "regular, ordinary," from Old French ordinel and directly from Late Latin ordinalis ""showing order, denoting an order of succession," from Latin ordo (genitive ordinis) "row, series" (see order (n.)). Meaning "marking position in an order or series" is from 1590s.