asigmatic,a.|eɪsɪgˈmætɪk| [f. a- 14 + sigmatic a.] Not sigmatic, formed without sigma. 1893F. W. Walker in Classical Rev. July 292/1 The one so called asigmatic tense that is not digammated is generally admitted to have dropped a sigma.1967Language XLIII. 628 An asigmatic aorist of khéō.