ectoparasite UK /ˌɛktə(ʊ)ˈpæɹəˌsaɪt/US /ˌɛktəˈpɛɹəˌsaɪt/ noun1 •A parasite that lives on the surface of a host organism; such as the Demodex mite, which lives in human hair and eyelashes.Ordinarily, allergy to animals is due to either their fine dander which becomes aerosolized or to the exoskeleta, pupae, or feces of their ectoparasites. — 1982 formsectoparasites