thyrotropinPronunciation: /ˌθʌɪrə(ʊ)ˈtrəʊpɪn/ (also thyrotrophin /-ˈtrəʊfɪn/)Definition of thyrotropin noun [mass noun] Biochemistry a hormone secreted by the pituitary gland which regulates the production of thyroid hormones. thyrotropin in other Oxford dictionaries Definition of thyrotropin in the US English dictionary