-έω

• -είω (-eíō) — Epic (etymology #3: verbs that are derived from adjectives in -ής (-ḗs) or neuter nouns in -ος (-os))

There are five main sources:

1. Primary verbs (present verbs of the simple thematic class in origin) from roots ending in *-w-, *-y-, *-s- with intervocalic loss of this consonant: e.g. ῥέω (rhéō), δέω (déō), ζέω (zéō)
2. Denominative verbs with *-eyéti, from *-e- (noun thematic vowel) + *-yéti (denominative suffix), usually from nouns or adjectives in -ος (-os) or -ον (-on): e.g. οἰκέω (oikéō) from οἶκος (oîkos), μετρέω (metréō) from μέτρον (métron)
3. Denominative verbs with *-esyéti, usually from adjectives in -ής (-ḗs) or neuter nouns in -ος (-os): e.g. τελέω (teléō) from τέλος (télos). These often have an alternative form in -είω (-eíō), for instance τελείω (teleíō).
4. Stative verbs with *-éh₁yeti (stative suffix): e.g. φιλέω (philéō), ἀλγέω (algéō)
5. Causative or frequentative verbs from o-grade of a root with *-éyeti (causative suffix): e.g. σοβέω (sobéō), φορέω (phoréō)

-έω • (-éō)

1. Used to form verbs from nouns, adjectives and other verbs. Often, not always, added to the stems of thematic nouns or adjectives in -ος (-os).

If the root lemma is a noun, then -έω is a denominative suffix, if an adjective -έω is a stative suffix, if a verb -έω is a causative or frequentive suffix.

• Sihler, Andrew L. (1995) New Comparative Grammar of Greek and Latin, Oxford, New York: Oxford University Press, →ISBN
• Smyth, Herbert Weir (1920) “Part II: Inflection”, in A Greek grammar for colleges, Cambridge: American Book Company, §§ 522.2, 866