An Etymological Dictionary of Astronomy and Astrophysics

1. (n) A proposition or situation offering a choice between two or more things only one of which may be chosen.
   
2. (adj) Offering or expressing a choice. → alternative energy, → alternatively.

Etymology (EN): Alternative, from → alternate.

Etymology (PE): Degarine, from degar “other,” variant digar, from Mid.Pers. dit, ditikar “the other, the second,” O.Pers. duvitiya- “second,” Av. daibitya-, bitya- “second,” Skt. dvitiya- “second,” PIE *duitiio- “second” + suffix -ine.