What are symptoms?

A symptom is a sign of something, usually not good.
For instance, a fever, runny nose, and sore throat may be a symptom of the flu. A loud knock may be a symptom that your engine has problems. Growling and snarling may be a symptom that your dog has aggression issues.
In medical terms, a symptom is a subjective indication of a disease or other physical condition.

For example, itchy eyes, sneezing, and swollen lips are some of the symptoms of an allergic reaction.
In medical terms, a symptom is a subjective indication of a disease or other physical condition.

Something that shows up or hints that something is different.