You seem to be talking about different things - the scientific community has an agreed upon definition, the 'scientific' definition, which cannot be easily redefined (any more than the scientific definition of a planet can be easily changed). However, by that same token, the Creationist community can indeed have their own definition - who gave scientists the sole right to define a term? In what Absolute Dictionary is the term written, and who gave scientists the Quill
Bingo. When restricting ourselves to the scientific definition, we qualify the term to mean one thing: the technical usage of scientists. That doesn't mean there cannot be non-scientists definitions.
I disagree, it absolutely does. Everyone defines their own terms, and jargon is born when groups of experts in the same field agree upon terms for niche and specialised concepts. That doesn't mean other people can't use the same word to mean something different - 'kernel' can refer to sweetcorn
and computer programming. Likewise, 'theory' can mean something in scientific parlance
and in Creationist parlance, with equal validity - we scientists do not get the sole ownership over the use of a word. We can't slap Creationists with copyright lawsuits because they didn't use a word in The Correct and Specified Way.
You are right that there is one
scientific theory, and that they are wrong to assert that Creationism is a theory according to the
scientific definition - but ours is not the only definition, and it is the height of arrogance to assert we are the sole owners of a word.