This past summer, the “Today” show used its Twitter account to share some news about the birth of an unusually heavy child. Along with a link to its story about the immense infant, “Today” included for its more than 2 million followers this brief note: “Woah baby! 13-lb. 7-oz. baby delivered in Spain.”

Surely the “Today” show knows how to properly spell “whoa.” But the TV show wasn’t the only mainstream news source reworking its spelling this past year to “woah.” Everyone was doing it.

But why? “Whoa” is hardly a new word; it dates back to at least the early 17th century. At that time it was used mostly in shouted form and was intended to garner the attention of someone in the distance. Around the mid-1800s, people began using “whoa” to halt forward-moving horses, and by the latter half of the 20th century it had morphed into an expression for conveying alarm, surprise or advanced interest. (Bill and Ted solidified the strength of this usage in 1989, Joey Lawrence sealed the deal during the ’90s, and Keanu Reeves reappeared to help usher the word into the new millennium via “The Matrix.”)

The expression is now exceedingly common, and this continuing ascension of its usage has overlapped with the advancing popularity of social media. With so many people using the word on Facebook, Twitter and other networks that drive Web traffic these days, it appears as though editors and writers this year felt they had little choice but to join the parade. By using “whoa” in headlines, as the opening word of published articles and pretty much everywhere else online, they seemed to be hoping that readers would see it and think: “Hey, what comes next must be really exciting, because there’s that same ‘whoa!’ all my friends use on Twitter when interesting and important things happen.”

But people were so busy writing that there was no time, apparently, to agree on how we all should be spelling it.

Merriam-Webster, a host of style guides and 259 likers of the Facebook page “It’s ‘Whoa’ not ‘Woah,” all support the traditional spelling of “whoa.”

Yet a simple Google search for “woah” brings up more than 5 million hits. And we can’t forget the spelling and grammar free-for-all that is the blogosphere, or the slapdash sentences that show up on message boards or the legions of Craigslist posters who used “woah” to jazz up apartment listings.

But where “woah” with the “h” at the end has really blown up is on social media. Typing the hashtag “woah” into the search box on Twitter at any given moment results in something on the order of 50 tweets an hour. Remove the number sign from the front of “woah” and the result is more like 50 tweets a minute. (“Woah he got pushed,” “Woah, where did my highlighter go?” and “WOAH! Heat wave! 34 degrees!”)

And if you were thinking you could perhaps quarantine yourself so as to preclude exposure to the “Today” show-style “woah” by avoiding all forms of social media and, say, spending some time relaxing in front of the TV, think again. This month, the History channel began airing an episode of its popular series “Pawn Stars” under the title “Woah Pilgrim.”

But wait. It appears there are even more ways to spell whoa. Some people feel the need to add an extra “h.” That’s right, “whoah.” Or sign in to Twitter and run a search on the craziest of all crazy attempted-whoa spellings, “whao.”

Is it just a typo, rather than a deliberate spelling? Maybe. But in this highly textual age, the typos of today can become the variant spellings of the future. What’s next, “whaoh”?