Reconstruction:Proto-Finnic/cööstäk

Etymology
, as per Koivulehto (2009), who proposed that the root can be considered a contracted variant of (compare e.g. ). In the past, considered a derivative of  (which would warrant the earlier reconstruction ): the basic meaning would thus be "to plunge, to go deep into smth." rather than, as suggested by Kulonen (2000), "(of water) to eat a path for itself".

Verb

 * 1) to push in, to plunge into
 * 2) to spew, to boil over