Merriam-Webster's Collegiate® Dictionary, 11th Edition
PRACTICE
I. verb also practise (practiced; also practised; practicing; also practising)
Etymology: Middle English practisen, from Middle French practiser, from Medieval Latin practizare, alteration of practicare, from practica practice, noun , from Late Latin practice, from Greek praktikē, from feminine of praktikos
Date: 14th century
transitive verb
1. carry out , apply , to do or perform often, customarily, or habitually , to be professionally engaged in ,
2. to perform or work at repeatedly so as to become proficient , to train by repeated exercises , plot , intransitive verb to do repeated exercises for proficiency, to pursue a profession actively, intrigue , to do something customarily, to take advantage of someone , practicer noun
II. noun also practise
Date: 15th century
1. actual performance or application , a repeated or customary action , the usual way of doing something , the form, manner, and order of conducting legal suits and prosecutions,
2. systematic exercise for proficiency , the condition of being proficient through systematic exercise ,
3. the continuous exercise of a profession, a professional business, see: habit