# porous portal

> English word · Noun

## Definitions
1. A type of extended and perforated tunnel portal on high-speed railways, designed to reduce the build-up of pressure when a train enters a tunnel at high speed.

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