ἐφ’ ὕδωρ

κλεψύδρα

A. keeper of the water-clock (κλεψύδρα) in the Athen. law-courts, Poll. 8.113 (but ἐφ’ ὕδωρ under water, submerged, CPR 32.11 (iii A.D.)).
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project