- Originally, denoting that the element to the name of which it is prefixed in the respective compounds exercised its highest valence; now, only that the element has a higher valence than in other similar compounds; thus, barium peroxide is the highest oxide of barium; while nitrogen and manganese peroxides, so-called, are not the highest oxides of those elements.
- A prefix used to signify through, throughout, by, for or as an intensive as perhaps, by hap or chance; perennial, that lasts throughout the year; perforce, through or by force; perfoliate, perforate; perspicuous, evident throughout or very evident; perplex, literally, to entangle very much.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). per-. Retrieved September 20, 2026, from http://smartdefine.org/per-/definitions/2043583 |
| Chicago | Webster's. 2011. "per-" http://smartdefine.org/per-/definitions/2043583 (accessed September 20, 2026). |
| Harvard | Webster's 2011, per-, Smart Define, viewed 20 September, 2026, <http://smartdefine.org/per-/definitions/2043583>. |
| MLA | Webster's. "per-" 27 May 2011. Web. 20 September 2026. <http://smartdefine.org/per-/definitions/2043583> |