-óir

• -eoir (slender form)

From Old Irish, from Latin -or.

-óir m

1. -er; suffix appended to words to create an agent noun, indicating a person who does (or a thing that does) something.

   ‎bád (“boat”) + ‎-óir → ‎bádóir (“boatman”)

   ‎Béarla (“English”) + ‎-óir → ‎Béarlóir (“Anglophone, English-speaker”)

   ‎focal (“word”) + ‎-óir → ‎foclóir (“dictionary”)

   ‎loisc (“burn, scorch”) + ‎-óir → ‎loisceoir (“incinerator”)

• The form is -eoir when the stem ends in a slender consonant.
• All nouns in -óir are masculine nouns of the third declension;
• When attaching to verbs, uses the participle form as the stem:

  cuidigh (“help”), pp. ‎cuidithe + ‎-óir → ‎cuiditheoir (“helper”)

  tiomsaigh (“collect, compile”), pp. ‎tiomsaithe + ‎-óir → ‎tiomsaitheoir (“collector, compiler”)

  tuismigh (“procreate”), pp. ‎tuismithe + ‎-óir → ‎tuismitheoir (“parent”)