NCIt definition : Straight elevated lines on the nail surface. Ridges may be vertical (running from
the cuticle to the nail tip) or horizontal (running from one side of the nail to the
other). Vertical ridges are usually not associated with underlying disorders and tend
to become more pronounced with age. Horizontal ridges may be associated with metabolic
disorders and malnutrition.;
Alternative definition : CTCAE: A disorder characterized by vertical or horizontal ridges on the nails.;