alternative

(noun) one of a number of things from which only one can be chosen. Synonyms: option, choice. Examples: "What option did i have?." "There no other alternative." "My only choice is to refuse."

(adj) serving or used in place of another. Synonyms: alternate, substitute. Example: "An alternative plan."

(adj) necessitating a choice between mutually exclusive possibilities. Example: "Alternative possibilities were neutrality or war."

(adj) pertaining to unconventional choices. Example: "An alternative life style."