Like Kūolka the name of Košrags appears in documents only starting with the 18th century. According to L. Kettunen the term may have come from the name of a river Koštõr-joug, he allows the possibility that the ending may stem from agja "edge, area" as well.
The etymology of the first component (Koštõr), however, remains unclear. Of interest is an early variant Košt-joug and Košt-joug-küla which would suggest that the first component might have been Košt- initially. Perhaps it comes from a shortened form of the Latin given name Constantinus. According to sources such names were given not only in the territory of Estonia but by Finnic peoples in Latvia as well: in 1289 – Coste in Riga, from 1355-1362 Coste around Kuldīga also in 15th century – Costi in Rūjiena. The form Kuošt- might have predictably been derived from Koosti common in Estonia but -rags, -rõg (commonly believed to be a Latvian element) might have been added according to the local tradition .[1]
Kuoštrõg
This term has open space locative forms: allative Kuoštrõgõlõ, adessive Kuoštrõgõl, ablative Kuoštrõgõld.
| singular (ikšlug) | plural (pǟgiņlug) | |
|---|---|---|
| nominative (nominatīv) | Kuoštrõg | – |
| genitive (genitīv) | Kuoštrõg | – |
| partitive (partitīv) | Kuoštrõgt | – |
| dative (datīv) | Kuoštrõgõn | – |
| instrumental (instrumentāl) | Kuoštrõgõks | – |
| illative (illatīv) | Kuoštrõgõ | – |
| inessive (inesīv) | Kuoštrõgs | – |
| elative (elatīv) | Kuoštrõgst | – |