atroceruleous

or at·ro·ce·ru·le·us, at·ro·coe·ru·le·us

[ a-troh-suh-roo-lee-uh s, -rool-yuh s ]
/ ˌæ troʊ səˈru li əs, -ˈrul yəs /

noun

a deep blue-black color.

Origin of atroceruleous

< Latin ātr-, stem of āter black + -o- + caeruleus azure; see cerulean, -ous