Any of a heterogeneous group of allergens that elicit manifestations of induced sensitivity (hypersensitivity) by direct contact with skin or mucosa. ... (05 Mar 2000) ... 
(kәn-tak´tәnt) an allergen capable of inducing delayed contact-type hypersensitivity of the epidermis after one or more episodes of contact.
Type: Term Pronunciation: kon-tak′tănt Definitions: 1. Any of a heterogeneous group of allergens that elicit manifestations of delayed hypersensitivity (allergic contact dermatitis after direct contact with skin or mucosa).
any substance that might induce an allergy by coming in contact with the skin or a mucous membrane.