» For other uses of athematic see Thematic. In the Indo-European languages, thematic roots are those roots that have a "theme vowel"; a vowel sound that's always present between the root of the word and the attached inflections. Athematic roots lack a theme vowel, and attach their inflections directly to the root itself. For example, consider the endings of the Latin "first declension" singular: Nom. rosa Gen. rosae Dat. rosae Acc. rosam Abl. rosā The vowel a s… (More on Athematic)