International Classification of Disease An internationally sanctioned system maintained by the WHO which standardises the terminology used for diseases, signs and symptoms, and external causes of injury. The ICD vocabulary set has over 14,000 different codes, and allows tracking of new diagnoses. With its optional sub-classifications, the set can be expanded to over 16,000 codes. The level of detail reported by ICD can be further increased using a multi-axial approach. The ICD is generally tailored to the coding needs of each country; the US version—ICD-10 CM (clinical modification)—has 155,000 codes.