blue-bellied
/ˌbluːˈbɛlɪd/adjective
1Especially in the names of animals: having a distinctive blue belly.
2 United States regional ( southern ). derogatory. Designating a person regarded as low, cowardly, or contemptible, especially (in the southern United States) a northerner (sometimes specifically a New Englander).
- From the mid 19th cent. sometimes with punning reference to the blue uniforms worn by Union soldiers..
Origin
Mid 18th century. From blue + bellied.