-τής

• -της (-tēs)

From Proto-Hellenic *-tās (whence also Mycenaean Greek 𐀑𐀴𐀲 (ki-ti-ta /⁠ktitā(s)⁠/, κτίτης)), probably a masculine formation from Proto-Indo-European *-teh₂ (perhaps still seen in Latin Monēta), feminine of *-tós. Originally used in adjectival compounds, the suffix's narrowing to agentivity may be by analogy to -τήρ (-tḗr) and -τωρ (-tōr).[1]

-τής • (-tḗs) m (genitive -τοῦ); first declension

1. Appended to verbs to form agent nouns

   ‎Βακχεύω (Bakkheúō, “to keep the feast of Bacchus”) + ‎-τής (-tḗs) → ‎Βακχευτής (Bakkheutḗs, “a Bacchanal”)

   ‎ἀγρεύω (agreúō, “to take by hunting”) + ‎-τής (-tḗs) → ‎ἀγρευτής (agreutḗs, “a hunter”)

   ‎αἰχμή (aikhmḗ, “a spear”) + ‎-τής (-tḗs) → ‎αἰχμητής (aikhmētḗs, “a spearman”)

   ‎αὐλέω (auléō, “to play on the flute”) + ‎-τής (-tḗs) → ‎αὐλητής (aulētḗs, “a flute-player”)

   ‎πειράω (peiráō, “to make an attempt on something”) + ‎-τής (-tḗs) → ‎πειρατής (peiratḗs, “a pirate, one who attacks ships”)

   ‎ποιέω (poiéō, “to make”) + ‎-τής (-tḗs) → ‎ποιητής (poiētḗs, “a maker”)

   1. With -ίζω (-ízō) verbs:

      ‎ἑλληνίζω (hellēnízō, “to speak the Greek language”) + ‎-τής (-tḗs) → ‎Ἑλληνιστής (Hellēnistḗs, “one who uses the Greek language”)

      ‎Ἡρακλειτίζω (Hērakleitízō, “to be a follower of Heraclitus”) + ‎-τής (-tḗs) → ‎Ἡρακλειτιστής (Hērakleitistḗs, “follower of Heraclitus”)

      ‎ἀγωνίζομαι (agōnízomai, “to compete for a prize”) + ‎-τής (-tḗs) → ‎ἀγωνιστής (agōnistḗs, “a competitor”)

      ‎βαπτίζω (baptízō, “to dip in or under water”) + ‎-τής (-tḗs) → ‎βαπτιστής (baptistḗs, “one that dips, a baptizer”)

      ‎κιθαρίζω (kitharízō, “to play the cithara”) + ‎-τής (-tḗs) → ‎κιθαριστής (kitharistḗs, “a player on the cithara”) (compare with the analogous recent guitarist)

   2. With -άζω (-ázō) verbs:

      ‎ἀγοράζω (agorázō, “to buy in the agora”) + ‎-τής (-tḗs) → ‎ἀγοραστής (agorastḗs, “the slave who bought provisions for the house”)

      ‎βιάζω (biázō, “to use force”) + ‎-τής (-tḗs) → ‎βιαστής (biastḗs, “one who uses force”)

      ‎δικάζω (dikázō, “to judge”) + ‎-τής (-tḗs) → ‎δικαστής (dikastḗs, “a judge”)

      ‎ἐνθουσιάζω (enthousiázō, “to be inspired by god”) + ‎-τής (-tḗs) → ‎ἐνθουσιαστής (enthousiastḗs, “one inspired by god”)

      ‎πελτάζω (peltázō, “to serve as a targeteer”) + ‎-τής (-tḗs) → ‎πελταστής (peltastḗs, “one who bears a light shield, a targeteer”)

   3. With -όζω (-ózō) verbs:

      ‎ἁρμόζω (harmózō, “to fit together”) + ‎-τής (-tḗs) → ‎ἁρμοστής (harmostḗs, “one who arranges or governs, a harmost”)

   4. With -ύζω (-úzō) verbs:

      ‎γογγύζω (gongúzō, “to murmur”) + ‎-τής (-tḗs) → ‎γογγυστής (gongustḗs, “a murmurer”)

• Latin: -tēs, -ta, -istēs, -ista, -astēs, -asta (see there for further descendants)

• -τήρ (-tḗr)
• -τωρ (-tōr)