Well, I checked my Encarta Dictionary and it says Practice is the only word, Practise being a spelling variation, Practice can be a noun and a verb, not like one being the noun, other being a verb.
prac·tice [práktiss]
verb (past and past participle prac·ticed, present participle prac·tic·ing, 3rd person present singular prac·tic·es)
1. transitive and intransitive verb repeat something to get better: to do something repeatedly in order to improve performance in a sport, art, or hobby
practices the piano daily
2. transitive verb do something as custom: to do something as an established custom or habit
3. transitive and intransitive verb work in law or medicine: to work in a profession, especially law or medicine
She has been practicing law for 15 years now.
4. transitive verb religion follow religion: to act according to the beliefs and customs of a particular religion
We are proud to practice the religion of our ancestors.
5. transitive verb perpetrate wrong: to perpetrate something morally bad such as deceit or cruelty (archaic)
noun (plural prac·tic·es)
1. repetition in order to improve: the process of repeating something many times in order to improve performance
2. process of carrying out an idea: the process of carrying out an idea, plan, or theory
It's more difficult to put these ideas into practice.
3. work of professional person: the business of a lawyer, doctor, dentist, or other professional
4. usual pattern of action: an established way of doing something, especially one that has developed through experience and knowledge
good business practices
5. performance of religion, profession, or customs: the performance of a religion, profession, set of customs, or established habit
Microsoft® Encarta® 2008. © 1993-2007 Microsoft Corporation. All rights reserved.