CINCINNATI — If you think a brown betty is an apple tart, you may not want to read further.

That’s not the meaning ascribed by Betty Beauty, a New York startup that is getting big PR play by marketing hair color for the nether regions. Billed as “color for the hair down there,” the company began really building buzz this summer with a brief appearance on the “The Tonight Show With Jay Leno” and mentions in magazines such as Vogue, W and People Style Watch.

Distribution so far is only in about 300 salons and beauty stores and via the website Bettybeauty.com. But helped along with a publicity push from LaForce & Stevens, New York, traffic to Bettybeauty.com, as measured by Alexa.com, was on pace last week for 2 million visits annually, running well ahead of Procter & Gamble Co.’s Clairol.com and climbing toward that of L’Oreal’s website.

That’s despite the fact that founder Nancy Jarecki’s first, and to date only, advertising expenditure was a $1,995 full-page ad in the official publication of the Cosmoprof beauty trade show in Las Vegas in July. By the time she registered for the show, the ad had already created enough buzz that several people around the table were asking her about it. The ad also helped draw the “Leno” team, which was taping a segment at the show. “It was just banter,” she said, along the lines of “It’s Betty — color for the hair down there.”

But it was enough to draw thousands of visits from people who did online searches even before her site was taking orders, Ms. Jarecki said. Mentions in magazines, on drive-time radio and on the website DailyCandy.com followed this summer and fall.

The whole thing started with Ms. Jarecki’s visits to a hair salon in Rome, where she was living three years ago. She noticed as women left the salon, the colorist would discreetly slip them little brown bags. “They would receive it with such delight, kiss kiss, and away they would go,” she said.

Curious, she asked the receptionist what the women were getting in those little bags and was told, in Italian, “to match down there.”

“I thought, ‘Of course, who wouldn’t want to be a true blonde?”‘ Ms. Jarecki said.

And so began research and development. Ms. Jarecki and a couple of female college students she hired called on women in salons and waxing parlors. “It came back that a lot of people would be interested in doing this,” she said, but safety concerns prevented them.

She also asked a gynecologist to track patients for a month (anonymously, of course). He had never paid much attention before in 25 years of practice, but he told Ms. Jarecki that “not one person matches.” A few blondes who had tried did so poorly, he told her.

So she worked with a chemist and toxicologist to develop a gentle, no-drip formulation and specialty application tools. Ms. Jarecki then wanted a brand personality she describes as a cross between Doris Day and porn star Traci Lords. The term “betty” came to mind as a term guys in college had applied to attractive women.

“People have always wanted a name to call their betty,” she said. “And I’ve been able to describe this product without having to say all the many types of ways to describe your betty.”

And so, another euphemism for the female anatomy is born. In five colors — Brown Betty, Blonde Betty, Auburn Betty, Black Betty and Fun Betty (hot pink) — priced at $20 a box. Bettybeauty.com also sells T-shirts that ask: “Is your betty ready?”

“Men can be betties, too,” Ms. Jarecki said, as some are buying Betty products. She knows because response rates for web questionnaires have been high. They also show surprising interest from women ages 60 to 85.

Beyond Betty, below the belt has become fertile ground for personal-care marketers lately. Philips Norelco caused a viral sensation with its Bodygroom and its website Shaveeverywhere.com, replete with influencer marketing via Howard Stern and a promise to add an optical inch to male anatomy.

Unilever’s Sunsilk is running magazine ads from WPP Group’s JWT, New York, for its De-Frizz products in which a curly-haired woman complains, “My hair’s so frizzy I should give it a Brazilian.”

But sales in the $1 billion mass-hair-color category were up only 0.7% in the 52 weeks ended Oct. 8, according to Information Resources Inc., with the main gainers being Revlon’s value brand and Combe’s Just for Men. Betty may be just what the market needs.