Many verbs in Old, Humanistic and Baroque Czech are derived using the prefixes s-, z- and vz-. These prefixes are semantically and functionally partly synonymic: they have both resulting and perfective meaning, and, moreover, they all undergo phonetic changes in connection with the consonantal beginning of verbal roots: s- → z-, z- → s-, vz- → z-, etc. As a result, many lexical units facilitate several explanations for their origin and meaning. Functionally useless verbs disappear over the course of time due to the economy of the lexical system. This occurs in several ways: 1) through the simple elimination of lexical units redundant in terms of functional use; 2) through the reduction of registered forms frequently accompanied by shifts in meaning; 3) through the diminishing of the level of Old- and Middle-Czech polylexy in favor of verbs derived using prefixes other than s-, z- and vz-; 4) through the substitution of the prefixes s-, z- and vz- with other prefixes, formally clearly distinguishable and less exploited in terms of function, meaning and frequency of use; or possibly 5) through the general re-evaluation of the meaning and comprehension of a lexical unit.