noun
: a member of a binary or multiple star system that is known to exist only by its gravitational effect on the visible components whose apparent motions it usually alters in a cyclic manner
noun
: a member of a binary or multiple star system that is known to exist only by its gravitational effect on the visible components whose apparent motions it usually alters in a cyclic manner
Webster's New International English Dictionary. Новый международный словарь английского языка Webster. 2012