σιγματίζω
From LSJ
ἔστιν δέ που ἡ μὲν ἐπὶ σώμασι γυμναστική, ἡ δ' ἐπὶ ψυχῇ μουσική → I think I am right in saying that we have physical exercise for the body and the arts for the soul
English (LSJ)
A write with sigma, διπλῶς σιγματίζεται is written with double ς, Eust.1389.15.
German (Pape)
[Seite 878] mit dem Sigma schreiben, das Sigma brauchen od. mißbrauchen, es zu oft brauchen, Eust.