The oldest known intraterminal base is that of the so-called aorist. This designation is potentially misleading, since the term ‹ἀόριστος› ‘indefinite’ is normally used for a particular kind of past tense in Indo-European languages. This traditional term will nonetheless be maintained here since the thematic base is indefinite in another sense. It is a specific morphological type that has changed its semantic function markedly in the course of the known Turkic linguistic history. It has mostly become strongly defocalized and modalized. With its evasive semantic profile, it cannot be defined as representing any consistent functional type. Independently of its various stages of development, it will be glossed as 〈aor〉, whereas the other intraterminal categories will be glossed as 〈intra〉.