σφραγιστήριον
From LSJ
κάλλιστον ἐφόδιον τῷ γήρᾳ ἡ παιδεία (Aristotle, quoted by Diogenes Laertius 5.21) → the finest provision for old age is education
English (LSJ)
τό,
A seal, stamp, PLond.5.1657.13 (iv/v A.D.); = signaculum, signatorium, Gloss.
German (Pape)
[Seite 1052] τό, Siegel, Petschaft, Sp.