Stop word
Certain words, such as "the," "a", "an," "of," and "with," are so common and meaningless that a search engine won't bother including them in their index, or database, of web page content. So in effect, the stop words on your web pages are ignored as if those words weren't on your pages in the first place. Including a lot of stop words in your title tag waters down the title tag's keyword density.
