alternative (n.) Look up alternative at Dictionary.com
1620s, in rhetoric, "proposition involving two statements, the acceptance of one implying the rejection of the other," from noun use of Medieval Latin alternativus "do one thing and then another, do by turns," from Latin alternus "one after the other, alternate, in turns, reciprocal," from alter "the other" (see alter). Of courses of action, from 1814. Of objects, etc., "the other of two which may be chosen," by 1836.
alternative (adj.) Look up alternative at Dictionary.com
1580s, "offering one or the other of two," from Medieval Latin alternativus, from Latin alternatus, past participle of alternare "do one thing and then another, do by turns," from alternus "one after the other, alternate, in turns, reciprocal," from alter "the other" (see alter). Meaning "purporting to be a superior choice to what is in general use" was current by 1970 (earliest reference is to the media); in popular music, by 1984 in reference to pirate radio. Alternative energy is from 1975. Related: Alternatively.