An Etymological Dictionary of Astronomy and Astrophysics

1. A prefix meaning “through, thoroughly, utterly, very."
   

2. Chemistry: A prefix used in the names of inorganic chemical compounds containing an element in its highest oxidation state or containing a large or the largest possible proportion of an element.

Etymology (EN): From L. per “through, during, by means of, on account of,” cognate with Pers. par-, pirâ-, as below; cf. Gk. → peri- “around, about, beyond;” O.C.S. pre-; Russ. pere- “through;” Lith. per “through;” Goth. fair-; Ger. ver-; O.E. fer-.

Etymology (PE): Par-, per-, variants of pirâ- “around, about,” from Mid.Pers. pêrâ; O.Pers. pariy “around, about;” Av. pairi “around, over,” per- “to pass over, beyond;”
cf. Skt. pari; Indo-Iranian *pari- “around;” cf. Gk. peri “around, about,
beyond;” L. per “through,” as above; PIE base *per- “through, across, beyond.”