The spine is a three dimensional structure and it has some normal or 'physiological' curves to it.
Spinal deformityy is the term used for an abnormal shape to the spine
Scoliosis is a lateral deviation of the spine.
Kyphosis is a 'hunching' or forward bending of the spine.
Kyphosis can occur for a number of reasons , such as after a fracture, after infection or just as part of abnormal growth