# tube train

> English word · Noun

## Definitions
1. A smaller-profile underground train which operates through the tube tunnels under London, which have a small cross section.

## Etymology
Probably named after the shape of the tunnels; the Tube is an informal name for London Underground which has been trademarked.

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