Real Dictionary

alternative
Alternative is used to describe something that is different from the usual things of its kind, or the usual ways of doing something, in modern Western society. For example, an alternative lifestyle does not follow conventional ways of living and working.
An alternative plan or offer is different from the one that you already have, and can be done or used instead.
countable noun: If one thing is an alternative to another, the first can be found, used, or done instead of the second.

alternative in American English
providing or being a choice between two or among more than two things
adjective: affording a choice of two or more things, propositions, or courses of action
noun: a choice limited to one of two or more possibilities, as of things, propositions, or courses of action, the selection of which precludes any other possibility

alternative in British English
adjective: presenting a choice, esp between two possibilities only
noun: a possibility of choice, esp between two things, courses of action, etc