1.anything agreed upon, a preconcerted signal, Hdt., Thuc.; so, δέλτον ἐγγεγραμμένην ξυνθήματα having symbols inscribed upon it, Soph.
2.a watchword, Hdt., Thuc., etc.; ς. παρέρχεται the word is passed round, Xen.; ς. παραδιδόναι, παραγγέλλειν to pass it, id=Xen.
3.any token or sign, Soph.