The Irish third declension is made up of both masculine and feminine nouns; however, certain suffixes tend to have the same gender. The nominative singular can end in slender or broad consonants.
The third declension is characterised by the genitive singular having a broad consonant (depalatisation if necessary) plus -a.
The dative singular is the same as the nominative singular.
The third declension plurals are strong plurals with very few exceptions.
There are many monosyllabic nouns of the third declension ending in a wide range of broad and slender consonants.
However, there are many polysyllabic nouns with typical suffixes. Many are used to create verbal nouns, which are in the third declension when used as substantive, e.g., tógáil. Others are used to create: agent noun, e.g., bádóir, cuiditheoir; abstract nouns, e.g., eolaíocht
A weak plural is characterised by the genitive plural having the same form as the nominative singular. There are very few nouns classed as such in the third declension.
A strong plural is characterised by the genitive plural maintaining the same form as the nominative plural. Strong plural forms found in the third declension are: