Onychosis
Onychosis is the technical term applied to any deformity or disease of the nails.

Onychia
Onychia is an inflammation of the matrix of the nail with formation of pus and shedding of the nail. Any opening of the skin allows the entry of bacteria, fungi or other foreign materials, which may result in onychia. Be careful not to cause abrasion or opening in the tissues.

Onychocryptosis
Onychocryptosis is an ingrown nail, which can affect either the fingers or toes. In this condition, the nail grows into the sides of the tissue around the nail. The movements involved in walking can press the soft tissue up against the nail margin, contributing to the problem. If the tissue around the nail isn't infected or if the nail isn't too deeply imbedded in the flesh, you can trim the corner of the nail in a curved shape to relieve pressure on the nail groove.

Onychogryposis
Onychogryposis is a thickening and increased curvature of the nail. It is also called ram's horn nail and is usually the result of injury to the matrix. It may be hereditary and can also occur as the result of long term neglect. It is most commonly seen in the great toe but may be seen in other toes as well as the fingernails. The nail usually has many crosswise grooves and ridges, is brownish in color, and one side of the nail grows faster than the other, curving the nail plate giving it its typical ram's horn configuration. The thick curved nail is hard to cut, so the nail remains untrimmed, adding to the severity of the problem. If no infection is present, you can trim the nail with the proper nail clipper and a file. Each of the grooves is a weak area of the nail plate. Trim the nail across the plate at a groove, taking only small bites, and the nail will break off when it has been trimmed halfway across.

Onycholysis
Onycholysis is the loosening of the nail without falling off, usually beginning at the free edge and continuing to the lunula. It is frequently associated with an internal disorder, trauma, infection, nail fungi, and allergy to nail enhancement products, or may result from certain drug treatments.

Onychomadesis
Onychomadesis is the separation and falling off of a nail from the nail bed. It can occur on fingernails and toenails. In most cases, the cause can be traced to a localized infection, minor injuries to the matrix bed, or a severe systematic illness. Some chemotherapy treatments or x-ray treatments for cancer may also cause it. When the cause is removed, a new nail plate will form. If onychomadesis is present, don't apply enhancements to the nail. If there is no active infection present, a basic manicure or pedicure service may be given.

Onychophosis
Onychophosis refers to a growth of horny epithelium in the nail.

Onychoptosis
Onychoptosis is the periodic sheddng of one or more nails, in whole or part. This condition might follow certain diseases such as syphilis, or can result from fever, trauma, system upsets or a reaction to prescription drugs.

Paronychia
Paronychia is a bacterial inflammation of the tissues surrounding the nail. Pus is usually present, along with gradual thickening and browning discoloration of the nail plate. Paronychia around the entire nail is sometimes referred to as runaround paronychia. Chronic paronychia is most often caused by a yeast infection of the soft tissues around the nail but can also be traced to a bacterial infection. Individuals who work with their hands in water, such as health care workers and food processors, are quite prone to this type of infection.