The Collaborative International Dictionary of English v.0.48:
Whether \Wheth"er\, conj.
In case; if; -- used to introduce the first or two or more
alternative clauses, the other or others being connected by
or, or by or whether. When the second of two alternatives is
the simple negative of the first it is sometimes only
indicated by the particle not or no after the correlative,
and sometimes it is omitted entirely as being distinctly
implied in the whether of the first.
And now who knows
But you, Lorenzo, whether I am yours? --Shak.
You have said; but whether wisely or no, let the forest
For whether we live, we live unto the Lord; and whether
we die, we die unto the Lord; whether we live
therefore, or die, we are the Lord's. --Rom. xiv. 8.
But whether thus these things, or whether not;
Whether the sun, predominant in heaven,
Rise on the earth, or earth rise on the sun, . . .
Solicit not thy thoughts with matters hid. --Milton.
Whether or no, in either case; in any case; as, I will go
whether or no.
Whether that, whether. --Shak.