περιστομίς

ίδος, ἡ
A. gauge or spanner for testing thickness of τόνοι, Ph. Bel. 54.46, Hero Bel. 108.8.
2. iron clamp, Apollod. Poliorc. 155.11.
3. π. φρέατος, puteal, Gloss.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project