ὀπισθέναρ
From LSJ
ἐν ταῖς ἀνάγκαις χρημάτων κρείττων φίλος → it is better in times of need to have friends rather than money, a friend in need is a friend indeed (Menander, Sententiae monostichoi 143)
English (LSJ)
ᾰρος, τό,
A the back of the hand, Poll.2.143, 144, 9.126.
German (Pape)
[Seite 358] αρος, τό, der Rücken der flachen Hand, Hippocr. u. Sp., vgl. Lob. zu Phryn. 870.
Greek (Liddell-Scott)
ὀπισθέναρ: -ᾰρος, τό, τὸ ὄπισθεν τῆς χειρός, «καὶ τὸ μὲν ἔνδοθεν τῆς χειρὸς σαρκῶδες ἀπὸ τοῦ μεγάλου δακτύλου μέχρι τοῦ λιχανοῦ, θέναρ καλεῖται, τὸ δὲ ἔξωθεν ὀπισθέναρ» Πολυδ. Β΄, 143, 144, Γαλην.