Now that “retweet” has been added to the Oxford English Dictionary, Twitter has cemented its presence in the American lexicon.

While that news does little for its business interests, other than furthering its legitimacy, something else may help its forecasts ­­­­— the social media Web site registered its best month of traffic ever in July.

According to the Web analytics firm ComScore, 32.8 million unique visitors went to the site in July, up 2 million over its June tally and nearly 4 million vs. May.

In a summer of uncharacteristically frequent breaking news stories, Twitter has been at the center of much of it, whether with the U.S. budget crisis or riots across the globe.

The site’s July numbers make it the country’s 34th most popular Web site, and though it trails Facebook, it has caught up with MySpace and LinkedIn.