Let's take a look at a few ways people use the word "evolution". There are undoubtedly many many more, but they usually fall under the general definiton "Change with respect to time". You might even say that evolution merely means "change".
  • Change with respect to time. It does not have to do with whether that change is for better or for worse, and does not say what the cause for the change is.

    For example, see stellar evolution.

  • In a more restricted sense, we might just say "evolution" when we are really talking about specific type of evolution. Often this omitted type is biology.

    For example, the biological evolution of a human: as you age your body does indeed become different.

  • Related to biological evolution is the fossil record. Sometimes people say "evolution" when they mean the change of lifeforms over the entire history of our planet.
  • Finally, there is a notion that is sometimes assumed: "Natural". This can be applied to either the broad biological evolution (our bodies age naturally), or the evolution in fossil record. The connotation of this naturality is that the change is caused by natural processes.
  • As Gritchka noted above, sometimes people mean "Darwinian evolution".
  • Other times, people say "evolution" in reference to abiogenesis, the creation of the very first life. This is in fact a correct use of the word evolution, but often is not appropriate to a discussion on "Evolution".
I'm not saying that you should always say "progressive naturally-induced change in existing life-forms over the history of life" instead of "evolution", but please remember to be careful when throwing around terms, especially if you switch definitions half-way through. This is so that whoever is listening to you knows what you're talking about, and it also helps to avoid accidental logical errors.

I have heard some people in the Evolution vs. Creation debate give plenty of evidence for progression in the fossil record -- something both sides will agree on -- yet never explain why it must be caused by (super)natural processes. This strikes me as odd because it is exactly what is being debated over. (Although they have demonstrated evolution, it is not in the appropriate sense) Fortunately, the debate usually goes back on topic.