PRINCETON, N.J. — As a serial snack-food entrepreneur, Warren Wilson is no stranger to the challenges of running a business.

In the early days of his first enterprise, selling funnel cakes at fairs, there was the time when, tired of losing money on inclement days, he bought weather insurance — and proceeded to lose even more money than he had when it rained. In the 1990s, he and his wife and business partner, Sara, once had to mortgage their house and sell off investments to make their company’s payroll.

But it still came as a bit of a shock when the Wilsons made what they thought was a routine move to register the trademark of their hot product — a flat pretzel snack called Pretzel Crisps — and it was contested by none other than Frito-Lay, the 800-pound gorilla of the snack food market owned by PepsiCo.

“This is so different from anything else we’ve faced because we’re not fighting a product in the supermarket, we’re not fighting against an institution like a bank, we’re not dealing with an act of nature,” Mr. Wilson said in an interview at his company’s headquarters here. “This fight is about a big company that wants to dominate the snack food category by crushing a little company like ours rather than by competing with us.”