Forms nouns from other nouns and adjectives with the sense of ‘person or thing connected or involved with, belonging to, having’. · Forms adjectives from other nouns and adjectives with the sense of ‘connected or involved with, belonging to, having’.
köken: From Old Irish -ach, from Proto-Celtic *-ākos, from Proto-Indo-European *-eh₂kos, *-eh₂ḱos, from a-stem suffix *-eh₂ + adjectival suffix *-kos, *-ḱos; compare Welsh -og. Doublet of -óg.
aile: -achán, -achas
Éire (“Ireland”) + -ach → Éireannach (“Irish (person)”)
Etymology tree Proto-Indo-European *-wós Proto-Indo-European *-iHwósder. Latin -īvuslbor. Portuguese -ivo Learned borrowing from Latin -īvus. Doublet of -io.