Ur·sa Ma·jor / ˈərsə ˈmājər/ Astron. one of the largest and most prominent northern constellations (the Great Bear). The seven brightest stars form a familiar asterism known by various names (esp. the Big Dipper and the Plow) and include the Pointers. ∎ [as genitive] (Ur·sae Ma·jor·is / ˈərsē məˈjôris/ ) used with a preceding letter or numeral to designate a star in this constellation: the star Delta Ursae Majoris.
Boswell's father, Lord Auchinleck (1706–82) gave the name Ursa Major to Dr Johnson.