πύνδαξ

Probably from Proto-Indo-European *bʰudʰmḗn, the same root of πυθμήν (puthmḗn, “bottom”) and Latin fundus (“bottom”). However the medial "-νδ-" is highly problematic, as well as the initial "π-" instead of "φ-" (since it was no longer followed by "θ").

πύνδᾰξ • (púndăx) m (genitive πύνδᾰκος); third declension

1. bottom of a jar, cup or other vessel
2. lid of a vessel
   • 2nd century BC, Problemata‎^[1], 938a:

     ἐπεὶ καὶ ἀμφορέως τὸν πύνδακα ἐᾱ́ν τις ἀφελὼν διὰ τοῦ πυθμένος τρῑ́βῃ ἕλκων ἔσω καὶ ἔξω, ψόφον ποιεῖ, ὥστε φεύγειν τὰ θηρία, ὅταν οἱ ὀπωροφύλακες κατασκευάσωσιν αὐτό.

     epeì kaì amphoréōs tòn púndaka eā́n tis aphelṑn dià toû puthménos trī́bēi hélkōn ésō kaì éxō, psóphon poieî, hṓste pheúgein tà thēría, hótan hoi opōrophúlakes kataskeuásōsin autó.

     When one takes off the lid of a jar and rubs it over the bottom drawing it in and out, it makes enough noise to frighten animals, when the watchers of the fruit do it.

3. hilt of a sword

• “πύνδαξ”, in Liddell & Scott (1940), A Greek–English Lexicon, Oxford: Clarendon Press
• πύνδαξ in Bailly, Anatole (1935), Le Grand Bailly: Dictionnaire grec-français, Paris: Hachette
• Beekes, Robert S. P. (2010), Etymological Dictionary of Greek (Leiden Indo-European Etymological Dictionary Series; 10), with the assistance of Lucien van Beek, Leiden, Boston: Brill, →ISBN