big dipper is a noun meaning "a group of seven bright stars in the constellation Ursa Major". It carries 2 recorded senses.
a group of seven bright stars in the constellation Ursa Major
elevated railway in an amusement park (usually with sharp curves and steep inclines)
Definitions, synonyms and semantic relations for big dipper come from Princeton University’s WordNet. Commonness is measured against a corpus of everyday English. Full sources and licences.