stel·lar / ˈstelər/ • adj. of or relating to a star or stars: stellar structure and evolution. ∎ inf. featuring or having the quality of a star performer or performers: a stellar cast had been assembled. ∎ inf. exceptionally good; outstanding: his restaurant has received stellar ratings in the guides. DERIVATIVES: stel·li·form / ˈsteləˌfôrm/ adj.