dys

Dys is a combining form or prefix of Greek origin (dys-, meaning bad, difficult, or abnormal). It is used in medical, scientific, and descriptive terms to indicate impairment, dysfunction, or atypical development. The prefix signals a departure from normal function or structure, rather than a simple negation. It is distinct from the Latin-derived prefix dis-, which is a different origin and set of usages, though both convey a sense of abnormality in many terms.

Common examples of dys in medical and related terminology include: dysplasia (abnormal development of tissue or organs), dysphagia (difficulty swallowing), dyspepsia (indigestion), dyslexia (a learning disability affecting reading), dysgraphia (difficulty with writing), dysphonia (disorder of the voice or hoarseness), and dysfunction (impaired function of an organ or system). Another related term is dyspnea, often spelled with a y in English, referring to shortness of breath.

In usage, dys forms adjectives and nouns across disciplines such as medicine, psychology, and biology, and it frequently describes conditions that are chronic, progressive, or congenital rather than temporary inconveniences. Because it is a Greek-derived prefix, it appears in many terms of both clinical and theoretical contexts, reflecting a spectrum of abnormalities rather than a single diagnosis.