bra·chi·o·saur·id 
(br
ā′k
ē-
ə-sôr
ĭd, br
ăk
′ē-)
n. Any of several very large herbivorous sauropod dinosaurs of the family Brachiosauridae of the Jurassic and Cretaceous Periods, having a long neck, small head, and front legs longer than the hind legs. Also called brachiosaur.
[From New Latin Brāchiosauridae, family name, from Brāchiosaurus, type genus; see BRACHIOSAURUS.]
bra′chi·o·saurid adj.