An Etymological Dictionary of Astronomy and Astrophysics
English-French-Persian

1) Of or relating to an order, as of animals or plants.
2) Of or relating to order, rank, or position in a series.
3) → ordinal number.

M.E., from O.Fr., from L.L. ordinalis "denoting order or place in a series," from L. ordo (genitive ordinis) "row, series," → order; → -al.

→ order; → -al.

1) A number which defines the position or rank of something in a series, in contrast to → cardinal number. For example, first, second, tenth, etc.
2) In → set theory, the order type of a → well-ordered set. Also called ordinal.

→ ordinal; → number.