Rabbits are NOT rodents.
More Info: While both are mammals, they are in different orders. Rodentia is the largest order of mammals, with 1,685 species. Rabbits are in the smaller Lagomorpha order that contains 63 species, including hares and pikas. The orders are closely related. In fact, they were once grouped together. However, these separate orders exhibit several defining differences.
Rabbits have an additional pair of tiny incisors compared to rodents, which have one large incisor in each jaw. A rodent incisor also tends to be sharper than a rabbits. All lagomorphs are herbivores while rodents are omnivores. The wide range of species within the order of Rodentia contributes to their vastly different habitats and areas where they give birth. Rabbits all give birth in nests lined with fur.
All mammals have similarities, such as an internal ability to maintain steady body temperature, hair and similar inner ear structure. The vast majority of mammals also give birth to live babies. A specific similarity is that both orders have unusually large pterygoid regions of the skull that reach back to the auditory region. This portion of the skull helps with movement of the lower jaw. This characteristic is unique to these two orders of mammals.
Allen G Collins, B. W. (1994, May). Introduction to the Rodentia. Retrieved 10 29, 2012, from http://www.ucmp.berkeley.edu/mammal/rodentia/rodentia.html
Southeast Missouri State University. (n.d.). Rodents and Lagomorphs. Retrieved October 29, 2012, from Southeast Missouri State University: http://www.google.com/url?sa=t&rct=j&q=&esrc=s&frm=1&source=web&cd=3&ved=0CCwQFjAC&url=http%3A%2F%2Fcstl-csm.semo.edu%2Fscheibe%2FMammalogy%2Frodents.ppt&ei=kZGOUNmGDeHzygHw2IHQCw&usg=AFQjCNEfVGrAjxQo4K358O3Q1FWlFGnJIw