Under Armour founder and CEO Kevin Plank. J. Meric/Getty Images Last year Under Armour passed Adidas as the second-most-popular athletic equipment and apparel company in the US, behind Nike.

The relatively new company in the industry has a fascinating origin story, particularly in how it got its name.

At first glance, it might seem as if the Baltimore-based company uses the British spelling of "armor" for faux sophistication or visual appeal.

But as CEO and founder Kevin Plank told The Washington Post last fall, it was actually the result of trying to get a cool toll-free phone number.

In fact, the entire naming process unfolded haphazardly, he said.

Plank, a former University of Maryland football player, began developing a proprietary sweat-wicking athletic undershirt out of his grandmother's townhouse in Georgetown in 1996.

He initially wanted to call the company Heart, as in "wearing your heart on your sleeve," but he couldn't obtain a trademark.

His next idea was Body Armor, a name he fell in love with, he told The Post. He applied for a trademark and prematurely told everyone that was the name of his company. But when the clearing process finished two weeks later, the trademark was once again denied.

The day Plank found out, he said: "I was a bit dejected, but I had lunch plans that afternoon with my oldest brother, Bill. So I show up to pick him up, knock on the door, and he looks down at me the way only an older brother can look at a younger brother, and he asks, 'How's that company you're working on, uhh ... Under Armor?'"

NBA MVP Stephen Curry's signature shoes by Under Armour. Thearon W. Henderson/Getty

Plank still doesn't know whether his brother was messing with him, but the name immediately clicked with him. He said he canceled his lunch plans and went home to fill out another trademark application. He received a trademark for Under Armour three weeks later.

"Oh, and the reason we added the 'U' in 'Armour' is that I was skeptical at the time about whether this whole internet thing would stick," Plank told The Post. "So I thought the phone number 888-4ARMOUR was much more compelling than 888-44ARMOR. I wish there was a little more science or an entire marketing study behind it, but it was that simple."

For more on the early days of Under Armour, you can read the rest of Plank's interview on The Washington Post's site.