Sure there is. It's called "degeneration" and it happens all the time.
That still isn't "de-evolution". It's evolution which leads to the loss of a feature.
And no, this is not just semantics. Labeling it "de-evolution" reveals a deep misunderstanding of what evolution is, and what it is not, plus it only reinforces false concepts about evolution, as in the following passage from a creationist website:
The existence of vestigial organs would not prove evolution anyway. Actually, they would prove degeneration, not evolution! Useless organs in our bodies would mean we were going backward, not forward. Evolutionists claim we are evolving upward, and then point to supposedly degenerate organs in our bodies to prove it.Practically every phrase in this passage is deeply in error, and it's all based on the author's misconception about what evolution actually is and what its results are -- on the misconception that "degeneration" is "anti-evolution" or "reverse evolution", when it's not, or that (another face of the same coin) evolution "requires" organisms to evolve "upward" (it does not) or that there even *is* an "upwards" with respect to fitness to survive or reproduce.
It would be like insisting on calling what an airplane does when it descends in altitude as "de-flying" (or "unflying", "anti-flying", etc.), under the mistaken impression that one is only "flying" when one is *gaining* altitude. But in reality the airplane is still flying as long as it is descending slower than a dropped rock. The process of using the wing's airfoils to resist the full effect of gravity is still "flying" in every legitimate sense of the word, even if you're in a descent.
Similarly, a feature being removed from the gene pool across generations due to the action of selective pressures is *still* "evolution", not "de-evolution".
Oops, I meant to ping you folks to post #900.
How very convenient of your personal thesaurus.
Tell that to democrats.