ἀρχοσυνάγωγος
From LSJ
καὶ τὸ σιγᾶν πολλάκις ἐστὶ σοφώτατον ἀνθρώπῳ νοῆσαι → and silence is often the wisest thing for a man to heed, and often is man's best wisdom to be silent, and often keeping silent is the wisest thing for a man to heed
Spanish (DGE)
presidente de un gremio o colegio, archisinagogo, encargado de la sinagoga; v. ἀρχισυνάγωγος.
