Oh my, said Alice to the Queen, Words mean just what you say they mean, nothing more and nothing less.

Or Humpty Dumpty to Alice or whatever.

It's always nice if, when confronted by a new word, that one can deduce its meaning from the word itself as well as from the context. Ignoring the fact that ex-wives don't necessarily cease to exist or even cease to be wives, they merely cease to be one specific person's wife, the word adapt breaks up into ad- and apt, the individual elements meaning toward, to and to become fit respectively. Exapt (not exadapt) breaks up into ex- and apt, the ex- meaning out of, from and the apt as before. In the former we are stressing that something has moved toward a use for which it has become fit and in the latter that it has moved from some other use to become fit for a new use. Pre-adapt sounds like introducing a woman as your future ex-wife.