Scoliosis is characterized by which of the following conditions?

Scoliosis is specifically characterized by a lateral, or side-to-side, curvature of the spine. This condition can occur in various degrees of severity and may affect individuals during different stages of life, particularly during growth spurts. The curvature typically appears in a "C" or "S" shape when viewed from the back.

Understanding scoliosis involves recognizing that it is primarily about how the spine deviates from its normal alignment in a horizontal plane. Thus, the key aspect of scoliosis is this abnormal lateral curvature, which distinguishes it from other spinal conditions that may present different types of curvatures or issues, such as kyphosis, which involves excessive forward curvature.

The other options describe conditions that do not accurately define scoliosis. Front-to-back curvature would refer to conditions like kyphosis or lordosis, excessive spinal length is not a characteristic of scoliosis, and weakness in spinal discs does not correlate with the spine's curvature but rather with degeneration or injury.