Part of speech:
Operating in a hidden or confidential manner:
The definition of hidden is concealed.
Of or characteristic of the activities of spies and undercover agents, esp. as extravagantly depicted in popular suspense fiction
(Figuratively) prepared for, or dealt with some matter
The definition of revolutionary is relating to political or social change.
Lying beneath the earth's surface; underground
Part or all of this entry has been imported from the 1913 edition of Webster's Dictionary, which is now free of copyright and hence in the public domain. The imported definitions may be significantly out of date, and any more recent senses may be completely missing.
Conducted in secret or through the use of subterfuge, as in a police investigation or in spying:
Being in a secret place; conducted secretly.
Secret, not spoken of (spoken of only in hushed whispers between insiders).
Situated or occurring below the surface of the ground:
(Electronics) An electron tube.
an electric railway operating below the surface of the ground (usually in a city)
For the sake of experiment; designed to test
The definition of avant garde is new and innovative in style or method, usually describing something in the arts.
(Biology) Ability (of an organism, tissue, or cell) to withstand a destructive agent or condition such as a chemical compound, a disease agent, or an environmental stressor:
A group of people who aid the enemy from within their own country
Located or situated on a lower level or beneath something else:
Designating or of the underworld of the dead and its gods or spirits
The definition of subversive is something that is trying to destroy or overthrow something like a government or an idea.
(Figuratively) Above the surface.
The definition of ground is base or beginning.
The atmosphere, as seen from a given point on the Earth's surface. The sky appears to be blue because the wavelengths associated with blue light are scattered more easily than those that are associated with the other colors.
Recognized, proven, etc.
The definition of public is something that is related to, available to or known by people.
The definition of legal is something connected to law or a government’s system of rules.
(Botany) Of or relating to seed germination in which the cotyledons remain below the surface of the ground.
Relating to or occurring on or near the surface of the earth.
Find another word for underground. In this page you can discover 59 synonyms, antonyms, idiomatic expressions, and related words for underground, like: secret, hidden, subterrene, buried, metro, cloak-and-dagger, covered, earthed over, hypogeous, beneath and revolutionary.