The Collaborative International Dictionary of English v.0.48:

Medication \Med`i*ca"tion\, [L. medicatio: cf. F.
   m['e]dication.]
   The act or process of medicating.
   [1913 Webster]

WordNet (r) 3.0 (2006):

medication
    n 1: (medicine) something that treats or prevents or alleviates
         the symptoms of disease [syn: medicine, medication,
         medicament, medicinal drug]
    2: the act of treating with medicines or remedies