Reconstruction:Proto-Slavic/-akъ

Inherited from Proto-Balto-Slavic *-āˀkas, from Proto-Indo-European *-eh₂kos, *-eh₂ks. Deverbal derivations are easily secondary, motivated by parallel formations, e.g.

• North Slavic *ědakъ (“greedy man”) ← *est < *ed-ti (“to eat”) : *ěda (“food”).

Comparison with cognates in other Indo-European languages indicates antiquity of deadjectival formations:

• Ancient Greek νέος (néos, “new, young”) → νέᾱξ (néāx), νέᾱκος (néākos, “young man”) : Slavic *novъ (“new”) → *novakъ (“novice”)
• Lithuanian naũjas (“new”) → naujõkas (“novice”)

Cognate with Proto-Celtic *-ākos (see Etymology 2).

*-akъ m

1. Deadjectival, forming nouns denoting a carrier of a property.

   *junъ (“young”) → *junakъ (“a young man”)

   *novъ (“new”) → *novakъ (“novice”)

   *lěvъ (“left”) → *lěvakъ (“left-handed man”)

   *svojь (“one's own”) → *svojakъ (“relative, cousin”)

2. Denominal, forming nouns denoting something connected in meaning to the base-word.

   *rodъ (“kin”) → *roďakъ (“relative, cousin”)

   *kory (“root”) → *koreňakъ (“native, one from the root”)

   *moře (“sea”) → *mořakъ (“sailor”)

   *ryba (“fish”) → *rybakъ (“fisher”)

3. Denominal, forming masculine counterparts of feminine nouns.

   *gǫsь (“goose”) → *gǫsakъ (“gander”)

4. Deverbal, from the root, forming agent nouns.

   *prositi (“to ask; beg”) → *prosjakъ >*prošakъ (“beggar; asker”)

• *-jakъ (causing iotation of the preceding consonant)

• Šekli, Matej (2012) “Besedotvorni pomeni samostalniških izpeljank v praslovanščini”, in Philological Studies‎^[1] (in Slovene), volume 10, number 1, Skopje, Perm, Ljubljana, Zagreb, pages 115–32
• Sławski, Franciszek, editor (1974), “*-akъ”, in Słownik prasłowiański [Proto-Slavic Dictionary] (in Polish), volume 1 (a – bьzděti), Wrocław: Ossolineum, page 89