Water that exists beneath the earth's surface in underground streams and aquifers.

(ornithology) The capercaillie, Tetrao urogallus.

An American game bird, Bonasa umbellus; the male makes drumming sounds with its wings

Alternative form of groundswell

A group of people who identify with one another, especially on the basis of ancestral, national, cultural, historical or religious grounds.

(aeronautics) A device which warns the pilot that the aircraft may be in danger of collision with the ground.

(physics) the propagation velocity of the envelope of a modulated travelling wave, which is considered as the propagation velocity of information or energy contained in it.

(physics) The stationary state of lowest energy of a particle or system of particles.

(mathematics) the set of rigid motions that are also affine transformations.

(mathematics) The group of all affine transformations of a finite-dimensional vector space.