Merriam-Webster President John Morse said "w00t" reflected the growing use of numeric keyboards to type words.
"People look for self-evident numeral-letter substitutions: 0 for O; 3 for E; 7 for T; and 4 for A," he said. "This is simply a different and more efficient way of representing the alphabetical character."
One Web site, www.thinkgeek.com, already sells T-shirts with the word "w00t" printed on the front.
"w00t belongs to gamers the world over. It seems to have been derived from the obsolete 'whoot' which essentially is another way to say 'hoot' which itself is a shout or derisive laugh," Think Geek said on its Web site.
The Top 10 list is here.