Definition of: whether

(hweth′ər) conj.
As the first alternative; in case; if: introducing an alternative clause, followed by a correlative or, or or whether; sometimes also introducing a single alternative, the other, usually a negative, being implied: Tell us whether you are going (or not).
—pron. Which: properly of two, less exactly of more than two: an archaism used interrogatively and relatively.
—whether or no Regardless; in any case. [OE hwæther, hwether]