The Greek pure verbs can be assigned to several derivational types in the preceding Proto-Indo-European language: Most of the verbs in -αω are derived from nominal ā-stems by forming the present tense with the suffix -i̯e-/-i̯o-: νικάω < *νῑκᾱ-i̯o- 'to win, prevail', from νίκα 'victory'; τιμάω < *τῑμᾱ-i̯o- 'to honor, revere', from τιμά 'honor'.
Verbs in -εω are derived from a range of nominal stems: φιλέω < *φιλε-i̯o- 'to love', from φίλος 'dear, beloved'; τελέω < *τελεσ-i̯o- 'to finish', from τέλος 'target, destination'; φωνέω < *φωνε-i̯o- 'to make a sound', from φονή 'sound'; μαρτυρέω < *μαρτυρε-i̯o- 'to testify', from μάρτυς 'witness'.
The verbs in -οω are mainly factitives derived from nominal o-stems: δηλόω 'to clarify, reveal', from δῆλος 'clear, obvious', δουλόω 'to enslave, conquer', from δοῦλος 'servant, slave'.
The following tables show the conjugated forms of the pure verb λῡ́ειν 'to solve; to free; to destroy' in classical Attic Greek.
In the present and imperfect tenses, the sounds represented by α and ο, in Attic Greek also ε, are usually merged with the following thematic vowel: τιμάω > τιμῶ 'I revere', καλέω > καλῶ 'I call'.