Who is an "alien"?

I'm trying to get to the bottom of how we determine who an "alien" is. Since it is all over SB 1070 there must be some extremely scientific and fool proof way of figuring this out. Let's see what definitions exist that can help clear this up...

Ahh, the IRS. They will have a clear cut answer. So, who is an alien?
To summarize:
You are considered a resident alien if you either meet the green card test or the substantial presence test. If you had a green card at some point during the year, Yea! You're a resident alien. If you were "physically present in the United States on at least 31 days during the current year, and 183 days during the 3 year period that includes the current year and the 2 years immediately before." http://www.irs.gov/taxtopics/tc851.html
Oh and you're exempt if you are a professional athlete doing some charity work, just sayin'.

If you don't meet these guidelines then you're a nonresident alien, an illegal alien, or a citizen...I think. They don't make this easy!

Okay, well that didn't help us. We know how to figure out if someone is a resident or a nonresident but why the word alien? What does it mean?

A dictionary must have the correct answer. Let's see what Definitions.net has to say about the meaning of the word alien. Here are a few excerpts from the list of possible definitions:
An alien is...
"1. (n.) alien
a foreign-born resident who has not been naturalized and who owes allegiance to another country.

3. alien
a person who has been estranged or excluded.

4. alien
an extraterrestrial.

7. alien
unlike one's own; strange.

8. alien
opposed; hostile (usu. fol. by to or from):
ideas alien to modern thinking."
http://www.definitions.net/definition/alien

Interesting. So we use the term alien for people who are not naturalized but we can also use the term alien for people who are strange or people who have been estranged. I'm seeing a value statement here? Anyone else?

Getting serious now...
This is where I see the problem. How can we call people by a term that sets them up to be excluded from community and society? Why is this okay? Yes, it's in the dictionary but we set the definitions. We choose how to define words and they are always evolving. It is time to use a different term. Something inclusive that does not have such a derogatory double meaning.