What does "apatosaur" mean?

A large, herbivorous, gregarious sauropod dinosaur, of the genus Apatosaurus, from Jurassic North America; it had a long neck and tail.

Apatosaur

Common synonyms include: apatosaurus, apatosaurus excelsus, brontosaur, brontosaurus, jurassic sauropod, large sauropod.

noun

noun ·Rare ·Advanced level

Noun

1
A large, herbivorous, gregarious sauropod dinosaur, of the genus Apatosaurus, from Jurassic North America; it had a long neck and tail.
2
huge quadrupedal herbivorous dinosaur common in North America in the late Jurassic wordnet

From scientific Latin Apatosaurus (genus name).