c. 1200, "contemplation; devout preoccupation; devotions, prayer," from Old French meditacion "thought, reflection, study," and directly from Latin meditationem (nominative meditatio) "a thinking over, meditation," noun of action from past participle stem of meditari "to meditate, think over, reflect, consider," frequentative form from PIE root *med- "to measure, limit, consider, advise, take appropriate measures" (cognates: Greek medesthai "think about," medon "ruler;" Latin modus "measure, manner," modestus "moderate," modernus "modern," mederi "to heal," medicus "physician;" Sanskrit midiur "I judge, estimate;" Welsh meddwl "mind, thinking;" Gothic miton, Old English metan "to measure;" also see medical).
Meaning "discourse on a subject" is early 14c.; meaning "act of meditating, continuous calm thought upon some subject" is from late 14c. The Latin verb also had stronger senses: "plan, devise, practice, rehearse, study."