ἡμιτόνιον

τό
A. semitone, Philol. 6, Aristox. Harm. p.21 M., al., D.H. Comp. 11, Arr. Epict. 2.11.2, etc.
II. half the skein or bundle of gut in a torsionengine, Ph. Bel. 68.46, Hero Aut. 2.6.
2. one of the two frames containing the τόνος in such an engine, Id. Bel. 90.4.
Liddell, Scott & Jones
A Greek-English Lexicon, 1940
An open-access project