Metro; an urban underground railway (subway). Often used for subway systems or company names (e.g., Tokyo Metro).
朝のラッシュはメトロがとても混む。
The metro is very crowded during the morning rush.
東京メトロの駅で待ち合わせしよう。
Let's meet at a Tokyo Metro station.
この街はメトロとバスが主要な交通手段だ。
In this city the metro and buses are the main forms of transport.
メトロの終電は何時ですか？
What time is the last metro train?