internal medicine
/ɪnˌtəːnl ˈmɛd(ɪ)s(ɪ)n/noun
1A medication administered or taken internally; †treatment using such medications (obsolete ).
2Chiefly US. A branch of medical practice dealing with the diagnosis and non-surgical treatment of diseases of the internal organs, especially in adults.
Origin
Mid 17th century; earliest use found in Certaine Statvtes Iustices & Officers of Peace. From internal + medicine.