ῥιζαῖος

α, ον
A. forming a base (cf. ῥίζα 11.2), ῥ. λίθος, of a column, opp. σπεῖρα, Sardis 7(1) No.181 (prob. i A.D.).
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project