Celinese: Nominal Categories: Ordinal Numerals: One-th, two-th, three-th

-at is the regular ordinal number ending:

1, 2, 3, 4 - Ainh, ðys/ðwy, trín, hyðor. 1st, 2nd, 3rd, 4th - ainhat, ðysat, trínat, hyðorat.