whether (conj.) Look up whether at Dictionary.com
Old English hwæðer, hweðer "which of two, whether," from Proto-Germanic *gihwatharaz (cognates Old Saxon hwedar, Old Norse hvarr, Gothic huaþar, Old High German hwedar "which of the two," German weder "neither"), from interrogative base *khwa- "who" (see who) + comparative suffix *-theraz (cognate compounds in Sanskrit katarah, Avestan katara-, Greek poteros, Latin uter "which of the two, either of two," Lithuanian katras "which of the two," Old Church Slavonic koteru "which"). Its comparative form is either. Also in Old English as a pronoun and adjective. Phrase whether or not (also whether or no) recorded from 1650s.