Onyxis is a medical term that refers to the condition of excessive thickening and curvature of the nails. It is often caused by trauma, fungal infection or a mineral deficiency. However, there are several synonyms for the word onyxis that are used in the medical field, including hypertrophy of nails, subungual hyperkeratosis, and pachyonychia. These synonyms are often used interchangeably depending on the context of the diagnosis. Patients with onyxis may experience discomfort and pain in the affected nails and require medical attention. Treatment options may include antifungal medications, surgery, or medications to address underlying medical conditions that contribute to the development of onyxis.