Tv b2 (us also alternate) an alternative plan or method is one that you can use if you do not want to use another one the opposition parties have so far failed to set out an alternative strategy.
Existing outside traditional or established institutions or systems an alternative lifestyle alternative energy.
Alternative | Definition of Alternative at Dictionary.com
Affording a choice of two or more things, propositions, or courses of action. (of two things, propositions, or courses) mutually exclusive so that if one is chosen the other must be rejected the alternative possibilities are neutrality and war.