Simple Definition:

Atopic refers to a condition characterized by an exaggerated immune response [reaction by the immune system] to certain substances (allergens) in the environment, leading to symptoms such as itching, redness, and inflammation of the skin or airways.

For example, someone with atopic dermatitis [a disease that causes inflammation of the skin] may experience itchy and inflamed skin after coming into contact with certain triggers like pollen or pet dander.

Very Simple Definition:

Atopic is a word used to describe when someone’s body reacts more strongly to things that cause allergies. This can make their skin or breathing feel itchy and irritated.

For example, if a person with atopic skin touches a cat, their skin might become red and itchy.