c. 1400, "to do, act;" early 15c., "to follow or employ; to carry on a profession," especially medicine, from Old French pratiser, practiser "to practice," alteration of practiquer, from Medieval Latin practicare "to do, perform, practice," from Late Latin practicus "practical," from Greek praktikos "practical" (see practical). From early 15c. as "to perform repeatedly to acquire skill, to learn by repeated performance;" mid-15c. as "to perform, to work at, exercise." Related: Practiced; practicing.
early 15c., practise, "practical application," originally especially of medicine but also alchemy, education, etc.; from Old French pratiser, from Medieval Latin practicare (see practice (v.)). From early 15c. often assimilated in spelling to nouns in -ice. Also as practic, which survived in parallel into 19c.