major planet
General term for a large planet, often used in contrast to minor planets or asteroids. In modern astronomy, it can refer to the eight planets of the solar system.
There are eight major planets in the solar system.
giant planet; Jovian planet
Specifically refers to the large gas or ice giants like Jupiter and Saturn, as opposed to terrestrial planets. Used in planetary science contexts.
See also: 木星型惑星
Jupiter is a typical giant planet.