An Etymological Dictionary of Astronomy and Astrophysics

A combining form meaning “half,” freely prefixed to English words of any origin.

Etymology (EN): From L. semi- “half,” from PIE *semi-; cf. Skt. sāmi “half,” sāmi-krita- “half-done;” Gk. hemi- “half;” O.E. sam-; Goth. sami- “half.”

Etymology (PE): Nim, nimé “half,” from Mid.Pers. nêm, nêmag “half;”
Av. naēma- “half;” cf. Skt. néma- “half.”