σεμνοπροσωπέω
From LSJ
ἀκμὴ οὐδὲ ἔχει γενέσεως ὑπόστασιν καθ' ἑαυτήν → the culmination has no power of originating by itself
English (LSJ)
A assume a grave, solemn countenance, ἐπί τινι Ar.Nu.363, cf. AP11.382.14 (Agath.).
German (Pape)
[Seite 871] eine ehrwürdige, ernsthafte, vornehme Miene annehmen; Ar. Nubb. 362; Agath. 69 (XI, 382); D. Cass. 65, 5.