Whether

(used to introduce the first of two or more alternatives, and sometimes repeated before the second or later alternative, usually with the correlative or )

It matters little whether we go or stay. Whether we go or whether we stay, the result is the same.

(used to introduce a single alternative, the other being implied or understood, or some clause or element not involving alternatives)

See whether or not she has come. I doubt whether we can do any better.

Archaic . (used to introduce a question presenting alternatives, usually with the correlative or ).

which or whichever (of two)? ?

whether or no

under whatever circumstances; regardless

He threatens to go whether or no.