-aí

• IPA^(key): /iː/

From earlier -aidhe, originally the Old Irish accusative and vocative plural ending of d-stem nouns. For example Old Irish arae, plural arada.

• -aidhe (obsolete)
• -í (slender form)
• -idhe (obsolete slender form)

-aí

1. Ending of the plural of certain nouns.

   ‎beannacht (“blessing, greeting”) + ‎-aí → ‎beannachtaí

   ‎gnólacht (“commercial firm”) + ‎-aí → ‎gnólachtaí

A merger of two different Old Irish suffixes. One the one hand, from Old Irish -id, from Proto-Celtic *-yatis, an extended variant of Proto-Celtic *-atis. On the other hand, from Old Irish -aige, from Proto-Celtic *sagyos (“seeker”).^[1]

• -aidhe, -oidhe, -uidhe (obsolete)
• -í (slender form)
• -idhe (obsolete slender form)

-aí m

1. -er (person or thing that does an action indicated by the root verb)

   ‎feighil (“to watch, tend”) + ‎-aí → ‎feighlí (“watcher, tender”)

2. -ist (one who follows a particular ideology; professional, amateur, or enthusiast; person who uses something)

   ‎Búda (“Buddha”) + ‎-aí → ‎Búdaí (“Buddhist”)

   ‎eol (“knowledge”) + ‎-aí → ‎eolaí (“scientist, -ologist”)

   ‎roth (“wheel”) + ‎-aí → ‎rothaí (“cyclist”)

3. -ee (person to whom, or a thing to which, an action is done; person who, or a thing that, does an action; person who is the recipient party to a contract)

   ‎fostaigh (“employ”) + ‎-aí → ‎fostaí (“employee”)

   ‎neamhláithreach (“absent”) + ‎-aí → ‎neamhláithrí (“absentee”)

   ‎morgáiste (“mortgage”) + ‎-aí → ‎morgáistí (“mortgagee”)

From Old Irish -ide, variant form of -de used after a syncopated vowel.

• -aidhe, -idhe (superseded)
• -í (slender form)

-aí

1. Added to nouns to form adjectives.

• -í (slender form)

-aí m

1. Suffix used to form verbal nouns

   ‎tosaigh + ‎-aí → ‎tosaí

   ‎fiafraigh + ‎-aí → ‎fiafraí