spherical aberration

This term is a technical specification used primarily in optics, astronomy, and ophthalmology. It describes a specific failure of a lens to focus all incoming light to a single point, which creates a "halo" or blur around the focal point. It is distinct from chromatic aberration, which involves the failure of different wavelengths of light to focus at the same point.

In a clinical context, this refers to a defect in the human eye's lens or cornea. Because it is a specialized scientific term, it is almost exclusively used in formal, technical, or academic registers and is rarely encountered in casual conversation.