I.to act as an ally, Il., Hdt., etc.; τινι to one, Thuc., etc.
II.generally, to aid or help at need, τινί Eur., Ar.: c. dat. rei, νόσοις ἐπικουρεῖν to aid one against them, Xen.; ἐσθὴς ἐπικουρεῖ τινι does him good service, id=Xen.; ἐπ. τροφῆι to make provision for it, Aeschin.
2.c. acc. rei, ἐπικουρεῖν τινι χειμῶνα to keep it off from one, Lat. defendere, Xen.