-икъ

Old Church Slavonic

-икъ • (-ikŭ) m

-er, -or; Deadjectival nominalizing suffix used chiefly to create a masculine agent noun from adjectives in -ин- and passive participles in -ен-.
- грѣшьнъ (grěšĭnŭ, “sinful”) + -икъ (-ikŭ) → грѣшьникъ (grěšĭnikŭ, “sinner”)
Isolated example is златикъ (zlatikŭ, “gold coin”), which has the suffix appended directly to the root злато (zlato, “gold”), and has diminutive (or singulative) meaning.

Declension of -икъ (o-stem)