"to treat medicinally," 1620s, a back-formation from medication, or else from Late Latin medicatus, past participle of medicare, medicari "to medicate, heal, cure" (poetic and Late Latin) from medicus "physician; healing" (from PIE root *med- "take appropriate measures"). Related: Medicated; medicating. The earlier verb in English was simply medicinen (late 14c.).
Medicaid
medical
medicament
Medicare
medicaster
medicate
medication
Medici
medicinal
medicine
medicine man