subterranean

[səbˌtəˈreɪniən]

Origin

From Latin "subterraneus": sub- (under) + terra (earth)

Meanings

1. Existing, occurring, or operating below the surface of the earth
2. Hidden, secret, or concealed

Example Sentences

1. The ancient city had an extensive subterranean network of tunnels and chambers.
2. Scientists discovered a subterranean lake beneath the Antarctic ice sheet.
3. The resistance movement operated through subterranean channels to avoid detection.

Related Words

• Noun: subterrane
• Adverb: subterraneanly
• Synonyms: underground, below-ground, subterrestrial, subsoil

Memorization Trick

Think "sub-terrain-ean": "sub" means under, "terrain" relates to land or earth, so "subterranean" is anything under the earth's surface.