How is 'chronic' best defined in medical terms?

In medical terminology, 'chronic' is best defined as a condition that is long-term and constant. This means that the condition persists over an extended period and typically does not resolve on its own. Chronic conditions can often be managed but may require ongoing treatment or lifestyle adjustments.

Chronic conditions can vary in severity and can include diseases such as diabetes, hypertension, and arthritis. The defining characteristic is their duration; they are not acute or sudden but rather developed slowly over time.

The other options describe different types of conditions. Sudden and severe refers to acute conditions, which occur quickly and often require immediate medical attention. Temporary and mild suggests a brief duration and less intense symptoms, while rapidly progressing implies a swift deterioration of health, which does not align with the nature of chronic conditions. Thus, understanding 'chronic' as long-term and constant provides clarity on its implications in medical contexts.