Are vertebrate wings and fins considered vertebrate limbs?
There is no alternative definition of "limb" in evolutionary biology. Legs, arms, wings and fins are all limbs. Note that a prehensile tail can also be called a limb. From wikipedia > limb


  A limb (from the Old English lim), or extremity, is a jointed, or prehensile (as octopus arms or new world monkey tails), appendage of the human or other animal body.


You can have a look at Cohn et al. (1997), where the term limb is used to refer to legs, arms, wings and fins.

Apparently some authors (as OP has shown examples in the comments) use the term differently. I think it is always made clear so as to not yield to any possible confusion. If you've ever been confused, you might want to let us know which article got you confused.