underground

Everyday

1. Underground means below the surface of the ground. tree →
2. The underground is a railway that runs in tunnels under a city (in London called the Tube; in the USA the subway). tree →
3. Underground can describe something secret or hidden from the authorities. tree →

In the lessons

In science lessons roots, burrows, caves, water and many animals (moles, rabbits, worms) live underground; coal and oil are found underground. In everyday life people travel on the underground. In history, people hid in underground shelters or ran underground groups. Phrases: go underground, underground station, underground train, underground water.

Examples

• Moles live underground. tree →
• Carrots grow underground. tree →
• We took the underground to the museum. tree →
• Mind the gap on the underground platform. tree →
• Rabbits dig underground tunnels called burrows. tree →
• Water flows underground in some caves. tree →
• Miners work deep underground. tree →
• During the war people sheltered in underground stations. tree →
• "They are playing at work underground, like moles," said she. tree →

Note

It can be an adjective (an underground cave) or an adverb (they live underground). «The Underground» with a capital U often means the London railway. In the USA it is the «subway»; in British English a «subway» is a tunnel for walking under a road. Never go into old mines or drains — they can flood or collapse.