Longman Dictionary of Contemporary English - whether

~ conjunction 1 used when talking about a choice you have to make or about two different possibilities  (He asked me whether she was coming. | The decision whether to see her was mine alone. | whether or not)  (I coudn't decide whether or not to go to the party.) 2 used to say that something definitely will or will not happen whatever the situation is  (I'm sure we'll see each other again soon whether here or in New York. | whether... or not)  (Whether you like it or not, you're going to have to face him one day.)  ( USAGE NOTE: WHETHER GRAMMAR Whether and if are often used in similar contexts. However, whether is usually used for if when you also use the word or especially at the beginning of a sentence. People say Whether you see her or not, phone me later. | If you see her, phone me. If can usually be used instead of whether with clauses following some verbs and adjectives I wonder whether/if she can come. | He wasn't sure whether/if he could come (NOT ...whether could he come). But you use whether (NOT if) before infinitives The question is whether to go or stay. Whether is also used after prepositions It depends on whether he's ready or not. It is also used after nouns It's your decision whether you go or stay. You often use whether with ...or not sentences, for example You're coming whether you like it or not. | We have to decide whether or not to support this proposal. SPELLING Note the spelling is whether (NOT wether). Wheather (=sunshine, snow etc) is a completely different word. )