drsným
The word "drsným" is the instrumental singular masculine or neuter form of the Czech adjective "drsný". In its core meaning, "drsný" translates to "rough," "harsh," "coarse," or "tough." The instrumental case in Czech is used to indicate the instrument or means by which an action is performed, or to express a characteristic that something possesses.
Therefore, "drsným" would be used in a sentence to describe something being done *by means of* something