-kki

From Proto-Finnic *-kkei, cognate with Estonian -k(i). Equivalent to -kka +‎ -i, and originally allomorphic with some uses of -kko (see -o).

-kki

1. Creates action nouns from verbs.

   levikki (“circulation of a newspaper”), from levitä (“to spread”)

   menekki (“sales, demand”), from mennä (kaupaksi) (“to sell”)

   hävikki (“loss (accounting)”), from hävitä (“to disappear. lose”)

2. Creates diminutive nouns from verb that indicate the object of an action.

   ajokki (“vehicle”), from ajaa (“to drive”)

   hoidokki (“patient”), from hoitaa (“to care”)

   lemmikki (“pet”), from lempiä (“to love”)

3. Creates nouns that indicate similarity, allegory or diminutiveness. The relationship is sometimes obscure.

   valokki, from valo (“light”)

   hanhikki, from hanhi (“goose”)

   punikki (“socialist (derogatory)”), from punainen (“red”)

   seitikki (“webcap”), from seitti (“gossamer, fine thread”)

   tyräkki

4. Creates female given names, especially for cows.

   Ainokki, from ainoa (“only”)

   Mielikki, from mieliä (“to desire”)

   Mustikki, from musta (“black”)

   Sarvikki, from sarvi (“horn”)

   Tuulikki, from tuuli (“wind”)

In some cases the usage is largely synonymous with -kko. As an example, the noun asukki (“inhabitant, often unwanted or temporary one”) from the verb asua (“to live in”) might as well be asukko.