-eći

Inherited from Proto-Slavic *-ęťьjь. In Proto-Slavic this was the ending of the present active participle, which was part of the inflectional system and could be formed for any imperfective verb (as is still the case in e.g. Russian, where the corresponding ending is -ащий (-aščij)/-ящий (-jaščij)), but in Serbo-Croatian this participle fell into disuse and survives only in certain lexicalized adjectives.

-ēćī (Cyrillic spelling -е̄ћӣ, adjective-forming suffix)

1. suffix forming a verbal adjective from the present tense of certain imperfective verbs, specifically those whose third person plural present tense ends in -ē, i.e. infinitives in -iti, -(i)(j)eti, some in -jati and a few others

   ‎rukovòditi (“to lead, to manage”) → ‎rukòvodē (“they lead, they manage”) + ‎-ēćī → ‎rukòvodēćī (“directive, leading, managing”)

   ‎póstojati (“to be, to exist”) → ‎póstojē (“they exist”) + ‎-ēćī → ‎póstojēćī (“existing”)

   ‎lèt(j)eti (“to fly”) → ‎lètē (“they fly”) + ‎-ēćī → ‎lètēćī (“flying”)

• -ūćī

Inherited from Proto-Slavic *-ęťьjь, from earlier Proto-Slavic *-ętjьjь, formed from *-ęt- (the stem of various nouns referring to young animals whose nominative ended in Proto-Slavic in *-ę) with the addition of *-jьjь, the same relational-adjective-forming suffix found in e.g. Serbo-Croatian bȉčjī (“bull (relational)”) (< Proto-Slavic *byčьjь < earlier *bykjьjь), formed from bȉk (“bull”) (< Proto-Slavic *bykъ).

-ećī (Cyrillic spelling -ећӣ, adjective-forming suffix)

1. suffix added to nouns referring to (usually) young animals, forming relational adjectives referring to the animal (not always specifically to the young animal)

   ‎jȁnje (“lamb”) + ‎-ećī → ‎jànjećī (“lamb (relational)”)

   ‎jȁre (“kid, young goat”) + ‎-ećī → ‎jàrećī (“kid, young goat (relational)”)

   ‎kr̀me (“pig; piglet”) + ‎-ećī → ‎kr̀mećī (“pig (relational); swinish, porcine”)

   ‎pȉle (“chick, young chicken”) + ‎-ećī → ‎pìlećī (“chicken (relational); chicken meat (relational)”)

   ‎Proto-Slavic *pьsę̀ (“puppy, young dog”) + ‎-ećī → ‎psȅćī (“dog (relational); canine”)