"pertaining or relating to the art or profession of healing or those who practice it," 1640s, from French médical, from Late Latin medicalis "of a physician," from Latin medicus "physician, surgeon, medical man" (n.); "healing, medicinal" (adj.), from medeor "to cure, heal," originally "know the best course for," from an early specialization of PIE root *med- "take appropriate measures" (source also of Avestan vi-mad- "physician"). "The meaning of medeor is based on a semantic shift from 'measure' to 'distribute a cure, heal'" [de Vaan]. The earlier adjective in English in this sense was medicinal. Related: Medically.

1917, short for medical examination. Earlier it was colloquial for "a student or practitioner of medicine" (1823).

"related to medicine in an auxiliary capacity," 1908, from para- (1) "subsidiary" + medical (adj.).

1650s, "physician; medical student," from Latin medicus "physician" (see medical (adj.)); modern sense of "serviceman in a military medical corps" is recorded by 1925.

"system for providing public funds to persons needing assistance with medical expenses," 1966; see medical (adj.) + aid (n.). The U.S. medical assistance program was created by Title XIX of the Social Security Act of 1965. 

"admitting of medical treatment, curable, healable," 1610s, from Latin medicabilis "curable," from medicare, medicari "to medicate, heal, cure" (poetic and Late Latin) from medicus "physician, healing" (see medical (adj.)).

mid-15c., "medical skill; a medicinal compound, a healing substance," from Old French médicament (15c.) and directly from Latin medicamentum "drug, remedy," literally "means of healing," from medicare, medicari "to medicate, heal, cure" (poetic and Late Latin) from medicus "physician; healing" (see medical (adj.)).

"medical technician," 1970, back-formation from paramedical. The meaning "medical corpsman who parachutes" is 1951 from parachute + medic.