From Wiktionary, the free dictionary
air fhichead
- twenty-
- Used behind the numerals for 1 - 19 and noun, if any.
- trì - three
- trì air fhichead - twenty-three
- trì leabhraichean air fhichead - twenty-three books
- trì deug air fhichead - thirty-three (vigesimal system, literally twenty-thirteen)