has part has part characteristic of has modifier Abnormal fingernail morphology Thin nail Thin fingernail No objective standard for nail thickness could be identified. An unsupported claim suggests that nails are 0.5 mm in females and 0.6 mm in males (http://www.emedicine.com/orthoped/topic421.htm). Thin nails are usually brittle, may easily fray, or break at the free edge. Thin nails usually grow slowly but this definition does not require slow growth of the nail. Note that the term koilonychia is an abnormal shape of the fingernail where the nail has raised ridges and is thin and concave. Since it include other characteristics besides thin nails, it should not be used to indicate this. The affected digits should be specified. abnormal decreased thickness nail of manual digit