1. Pertaining to, or living habitually on, the land or ground surface: Most domestic animals are terrestrial and exist on the surface of the ground.
2.Regarding life or development in or on the land: Most terrestrial plants thrive very well on good soil.
3. Relating to the land or to the planet Earth: Jim had to plow his terrestrial fields for the upcoming season.
4. Concerning the Earth or its inhabitants: Examples of terrestrial residents or dwellers in the world are people, animals, and plants.
5. Pertaining to a worldly, mundane character or quality: Sam was a very down-to-earth person who had a quite terrestrial nature and lived in an ordinary way.
6. Refering to, or composed of land: William's property was terrestrial with no lakes or streams.
7. In biology, pertaining to something living or growing on land; not aquatic_ The students learned in class that terrestrial plants or animals were those that did not live in seas or oceans.
8. Etymology, about 1432, from Latin terrestris "earthly", from terra "earth". Originally opposed to celestial; natural history sense of "living on land" is attested from 1638. The noun meaning "a human being, a mortal" is recorded from 1598.

The generic term for scintillation phenomena observed in light that reaches the eyes from sources liying within the Earth's atmosphere: An atmospheric boil, or a scintillation, refers to the rapid fluctuations in the amplitude and phase of electromagnetic or acoustic waves that have propagated through a medium containing fluctuations in refractive index, such as the atmosphere.

The most common example of optical scintillation is the "twinkling" of stars observed through the atmosphere because it arises as a result of random angular scattering produced by refractive index fluctuations.

Fluctuations in the amplitude of different frequency components in the spectrum of an object can give rise to apparent changes in its color (chromatic scintillation). An example is the random red and blue twinkling of bright stars near the horizon.

Scintillation statistics have been used to study turbulence in regions ranging from the planetary boundary layer to the ionosphere, as well as interplanetary and interstellar space and it is important for astronomical imaging, optical and radio communications, laser and acoustical propagation, active and passive remote sensing, and the performance of the Global Positioning System.

The world-wide system of latitude and longitude used to define the location of any point on the Earth's surface or to designate both geodetic coordinates and astronomical coordinates: Geographic coordinates refer to the quantities of latitude and longitude which define the position of a point on the surface of the Earth with respect to the reference spheroid.

Carbon that is contained in vegetation and soil: Tom had his garden soil tested and it turned out to contain terrestrial carbon, which had many positive aspects, like increasing microbial activity.

A collective term for all natural electrical phenomena of the Earth; geoelectricity: Terrestrial electricity includes atmospheric electricity:

Radiant energy emitted by the Earth: Terrestrial energy includes not only the forces and power from the ground, but also the atmosphere of the globe.

Any planet that is near the sun and has a similar size and density: Mercury, Venus, Earth, and Mars are all terrestrial planets and are composed mainly of metals and rocks, in comparison to gas planets.

Electromagnetic radiation originating from Earth and its atmosphere: Terrestrial radiation is the total infrared energy emitted by the Earth and its atmosphere and is measured at wavelengths that are determined by their temperature.

Terrestrial radiation is the radiation that is released by naturally occurring radioactive materials in the Earth; such as uranium, thorium, and radon.