συσφαιριστής

οῦ, ὁ
A. one who plays at ball with another, Pl. Ep. 363d, Ath. 1.19a (as cited by Suid. s.v. σφαῖρα), Antyll. ap. Orib. 6.32.3; dat. pl. συνφαιρονταῖς dub. in IG 22.4794.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project