The word that tripped him up was "porwigle," which means tadpole. Frank spelled it with two g's. Earlier tonight he correctly spelled "dedans," which refers to the spectators at a court-tennis match. His performance means he finished in seventh place.
The winner was Snigdha Nandipati of California. The word she correctly spelled to win the title was "guetapens" (ambush).
Frank, 14, an eighth-grader at Ave Maria Catholic School, maintained a smile and his poise after leaving the stage, but acknowledged he was disappointed.
Win or lose, he said before the finals, he's happy with his performance.
"I just wanted to come to the nationals," he said. "So everything is just icing on the cake ... I got to the finals. I think that's a pretty amazing accomplishment for the first time. Top nine out of 12 million spellers? I am very thankful."
Frank was poised and outwardly calm in front of the microphone, but he acknowledged it was a façade.
"On the inside, I am thinking, I'm nervous, I'm excited, my mind's a whirlwind," he said before taking the stage for the finals.
Frank was one of nine finalists and the only finalist from Colorado.
The other Colorado speller, 13-year-old Eva Kitlen, was eliminated Wednesday. Eva, a Longmont seventh-grader, correctly spelled "genre" (a class or category of artistic endeavor), and "utile" (useful), but her performance on Tuesday's written test kept her from advancing.
Eva, who attends Sunset Middle School, is eligible to return next year. Frank is not because he is the maximum eligible age for bee contestants. High school students also aren't eligible.
"He's still spectacular," Frank's mother, Jill Cahill, said after Frank left the stage. "He's a great kid - humble, empathetic, well-rounded. That's a blessing."
His father, Mike Cahill, said he's happy his son remained driven and passionate over 11 months of intense preparations with the help of a spelling coach - 1989 national champion Scott Isaacs. Mike Cahill - a self-described "horrible speller" - said he sought Isaacs' help because he couldn't help Frank prepare.
He said he told his son, "The elbow grease is up to you. I'll provide the framework."
In this morning's semifinal rounds, Frank correctly spelled "drosophila" (a type of fruit fly used in genetic research), "cannelon" (a hollow cone or roll filled with meat, cheese or cream), and "guilloche" (an ornamental pattern made by interlacing lines).
To advance to the semifinals, Frank nailed "frangible" (easily breakable) and "ephemeral" (short-lived), and his oral-round scores combined with his performance on the written round was enough to propel him to the semis.
According to the spelling bee's official biography, Frank's best subject in school is math. He was a Colorado state finalist in the MATHCOUNTS National Competition last year and this year. He also plays the violin and the piano, is active in the theater, plays basketball and lacrosse, is a Boy Scout and maintains a 4.0 grade point average.
This year's bee began with 278 spellers. Participants included the youngest recorded speller ever to compete in the national bee - 6-year-old Lori Anne Madison of Woodbridge, Va., who didn't make it to the semifinals - and two spellers making their fifth appearances. Countries represented in addition to the U.S. included Japan, New Zealand and Ghana.
Fifty semifinalists began spelling Thursday morning. This year's champion will claim $30,000, a $5,000 scholarship and other prizes.
-Raju Chebium - Gannett Washington Bureau