What does "aggressor" mean?

During the testimony of Chuck Phelps there was a brief point where the question, "What does aggressor mean?" was addressed.

This blog post does an excellent job of addressing the question:

Term of the Day: Aggressor

Reminds me of a question I read on the Stuff Fundies Like Forum from Mommy2Kids:

So does Chuck Phelps have a problem answering direct questions or does he just have a problem telling the truth?

It's pretty much incomprehensible to me that someone will intentionally obfuscate the meaning of the word "aggressor" (or that anyone will believe it!), but people will do desperate things when they are trying to cover up the ugly truth.