sick

Sick is a word with multiple related meanings. In a medical sense, it most often describes a person who is ill or unwell, as in having symptoms such as fever, fatigue, or a cough. It can also refer to the sensation of nausea or the act of vomiting, as in “to feel sick” or “to get sick.” In everyday speech, “sick” can also function as slang meaning very impressive or excellent, a usage common among younger speakers.

Medical context and common causes. Illnesses range from mild, self-limiting conditions to more serious diseases. Common infectious causes include viral upper respiratory infections, flu, stomach flu, and foodborne illness. Noninfectious causes of sickness can involve allergies, migraines, dehydration, or chronic conditions such as asthma or diabetes. The duration and severity of illness vary widely. Most mild illnesses improve with rest, fluids, and basic care, while more serious symptoms require medical attention.

When to seek care. Seek prompt evaluation for high fever, chest pain or shortness of breath, severe dehydration, confusion, persistent vomiting or diarrhea, severe headache, or symptoms lasting more than a few days or worsening over time. Individuals with underlying health conditions, pregnant people, and young children may require earlier medical advice.

Regional and social notes. In American English, “sick” commonly means ill or nauseated, and “sick day” refers to taking time off work for illness. As slang, “sick” can denote something remarkable or extreme, though usage varies by region and context.