Severe means harsh, strict, or serious in various contexts, such as treatment, appearance, illness, or weather. Find out the different meanings, examples, and related words of severe from various dictionaries and thesaurus. Severe definition: harsh; unnecessarily extreme .. See examples of SEVERE used in a sentence. SEVERE definition : 1. extremely bad: 2. not kind or gentle: 3. A severe person looks unfriendly or very strict.. Learn more. severe, stern, austere, ascetic mean given to or marked by strict discipline and firm restraint . severe implies standards enforced without indulgence or laxity and may suggest harshness.