alternative in WordNet English dictionary

1. serving or used in place of another
   "an alternative plan"
   alternate  alternative  substitute 
   
2. necessitating a choice between mutually exclusive possibilities
   "alternative possibilities were neutrality or war"
   alternative 
   
3. pertaining to unconventional choices
   "an alternative life style"
   alternative 
   

1. one of a number of things from which only one can be chosen
   "what option did I have?"; "there no other alternative"; "my only choice is to refuse"
   option  alternative  choice