The title of the legislation passed in October of 2002 was Joint Resolution to Authorize The Use of United States Armed Forces Against Iraq.

Text here.

A lot of effort has been made to try to spin this into something other than an authorization of the use of armed force against Iraq, particularly by those cowards in the legislature who voted for it when the political wind was blowing that way, but now are trying to weasel out of it when the wind has changed.

The intent of this resolution seemed pretty clear to me at the time, and while you can probably make a case that it's not a formal declaration of war in that many words, it is what it is.