asterism (n.) Look up asterism at
1590s, "a constellation, a group of stars," from Greek asterismos "a marking with stars," from aster "star" (see star (n.)). Originally any grouping of stars, whether a constellation or not; in modern use usually the latter. The "Big Dipper" is an asterism; Ursa Major is the constellation which contains it. Other examples are the "Summer Triangle," "the sickle" of Leo, "the teapot" of Sagittarius.