Wiktionary
n. Any planet of the solar system or any exoplanet which is "Earth-like" in the sense that it is composed primarily of metals and rock, in contrast to a planet which is a gas giant.
WordNet
n. a planet having a compact rocky surface like the Earth's; the four innermost planets in the solar system
Wikipedia
A terrestrial planet, telluric planet, or rocky planet is a planet that is composed primarily of silicate rocks or metals. Within the Solar System, the terrestrial planets are the inner planets closest to the Sun, i.e. Mercury, Venus, Earth, and Mars. The terms "terrestrial planet" and "telluric planet" are derived from Latin words for Earth (Terra and Tellus), as these planets are, in terms of composition, "Earth-like".
Terrestrial planets have a solid planetary surface, making them substantially different from the larger giant planets, which are composed mostly of some combination of hydrogen, helium, and water existing in various physical states.
Usage examples of "terrestrial planet".
They're going to have diplomatic problems enough splitting up the Jovian moons and the new terrestrial planet.
A terrestrial planet of a neighboring star is a hundred times fainter still.
Mapping the entire star at a resolution guaranteed to reveal or rule out even a Shanghai-sized pre-Introdus city was a task akin to mapping every terrestrial planet in the Milky Way.
The Tines' world was as Jefri Olsndot advertised, a normal terrestrial planet.
And the most important implication: It would be their only opportunity to see directly inside a terrestrial planet.
A large moon, approaching lunar proportions, circles the in- ner terrestrial planet.