O

Obesity: defined as BMI 30 denoting an excessive accumulation of fat on the body.

Oedema: swelling.

Omega - 6 polyunsaturated fat: an essential fatty acid important in the management of heart disease.

Omega-3 fatty acids: an essential fatty acid important in the management of heart disease.

Onychochauxis: abnormal but uniform thickening of the nail.

Onychocryptosis: when a spike, shoulder or serrated edge of the nail pierces the epidermis of the sulcus and penetrates the dermal tissues.

Onycholysis: Loosening or separation of a nail from its bed.

Onychogryphosis: abnormal elongation and twisting of the nails, giving a claw-like appearance.

Oral hypoglycaemic agents: oral medications that are used to control blood glucose levels.

Orthosis/orthotics: devices to correct deformities or improve functioning.

Osteoarthropathy: any disease of the joints or bones.

Osteomyelitis: inflammation of the bone caused by a pyogenic microorganism.