What does it mean to be an invertebrate?

Being a vertebrate means having a vertebra - the Latin term for backbone. Vertebrates include fish, amphibians, reptiles, birds and mammals (including humans). Everything else in the animal kingdom is invertebrate, without bones. Many invertebrates have an exoskeleton of hard plates, like the armour of an insect, or the shell of a slug. Others are soft and naked like jellyfish.

So, if it has bones, it´s a vertebrate. ^^