S / sēmĭ-tŏnĭum
noun hapax

sēmĭ-tŏnĭum

gen. sēmĭ-tŏni · gender neuter · decl. 2nd
a halftone; semitone
a halftone, semitone, Macr. Somn. Scip. 2, 1 fin.