# Porro prism

> English word · Noun

## Definitions
1. A reflection prism used in optical instruments to alter the orientation of an image. It consists of a block of glass shaped as a right geometric prism with right-angled triangular end faces.

## Etymology
Named after its inventor, Ignazio Porro.

## Source
Compiled from Wiktionary via kaikki.org (CC BY-SA). Data vintage: 2026-05-06.
Canonical page: https://plainspell.com/en/word/porro-prism