Scoliosis is coming from Old Greek σκολίωσις (skoliosis) meaning bending and is a medical condition where a patient has a spinal axis with a 3-Dimensional deviation composing like a "C" or a "S" for exemple in place of a relative straight line (vertical axis is supposed straight seen from front or rear of the body).
This can be congenital or due to work, position, attitude, ... who can cause progressive deviation or neuromuscular condition.
Source: Thermography by Pr. J.T. Valdez