WASHINGTON — Convinced she was about to win the National Spelling Bee, 13-year-old Rebecca Sealfon shouted each letter of her last word into the microphone “e-u-o-n-y-m” and raised her arms high.

“Yeah!” she screamed Thursday before balancing the trophy cup atop her head. The home-schooled teen-ager from Brooklyn, N.Y., placed eighth in the Scripps Howard-sponsored contest last year, but this year she was the champ, beating out Prem Murthy Trivedi, 11, of Howell, N.J.

“I knew I could figure it out,” Sealfon said about “euonym,” defined as an appropriate name for a person, place or thing.

She won $5,000 — which she plans to save for college — books and other prizes, including a laptop computer. Trivedi earned $4,000 for his second-place finish. Sudheer Potru, 13, of Beverly Hills, Mich., won the $2,500 third-place prize.

“This was incredible luck,” Sealfon said. “There were words I did not know in every round.”

Paul S. Crowley, 13, a seventh-grader at Middle School of the Kennebunks in Kennebunk, got through the fourth round Thursday but was tripped up in the fifth round.

Crowley, who was sponsored by the Bangor Daily News, correctly spelled “i-n-c-o-m-m-o-d-i-n-g” to advance to the fifth round, along with about 60 other spellers. The word means “inconveniencing.” But he misspelled “p-h-i-l-i-p-p-i-c,” a noun that means “tirade.” Crowley spelled the word with one “p” where the pair should have been.

Sealfon was so nervous that she asked to wait her turn off the stage. Rumors circulated that she was sick, but Sealfon said she was just nervous. “I couldn’t stand it,” she said.

Jittery or not, she spelled 22 words correctly, including “vaporetto,” a small steamboat; “hippogriff,” a legendary animal; and “bivouac,” a temporary camp. Her first challenge was the 16-letter word “sesquicentennial.”

Some of the 245 contestants spelled words by syllables. But Sealfon spelled letter-by-letter, often stopping after each one to cup her hands over her mouth. “I was thinking what letter was next and I was whispering the letter to myself,” she explained.

After each success, she raised her arms in the air and bounded off the stage.

For the last nine rounds, she battled only Trivedi, who was competing in the national spelling bee for the third time. Trivedi lost after he added an extra “l” to the word “cortile,” a courtyard.

Trivedi, who likes to study archaeology, swim and play chess and basketball, remained poised throughout the contest, calmly enunciating each letter into the microphone. He was disappointed, but said he’ll try to qualify again next year.

Nerves began to fray Thursday as the two-day competition droned on, speller-by-speller, word-by-word, letter-by-letter. As the competition progressed, the words got harder and more spellers were disqualified.

Briana Lyn Delaney, 13, of Lake Charles, La., correctly spelled “nuciform,” “lienholder” and “postponable.” But the seventh-grader who likes to write stories and poems in both English and French was tripped up by her fourth word.

“Araneiform?” she asked in disbelief. The word means like a spider.

She pronounced it twice. The pronouncer repeated the word. Then, Delaney said it again.

“What is the language of origin?” she asked, stalling.

She repeated the word two more times into the microphone, then asked the pronouncer to use it in a sentence. “Oh, OK,” she said, and she proceeded to misspell it “a-r-a-n-e-a-f-o-r-m.”

The bell dinged. Delaney, dressed in a long blue skirt, bobby socks and pink shoes, walked off the stage, her head hanging down as she clutched a small stuffed toy.

The contest, however, was not without humor.

Courtenay L. Glisson of Oxford, Miss., asked for her word, “succorance,” to be defined and used in a sentence. Looking for more clues, she finally asked the official pronouncer: “You have anything else you can give me?”

The audience laughed.

“It’s a noun,” offered pronouncer Alex J. Cameron, chairman of the English department at the University of Dayton, Ohio.

Glisson tried to spell it, but failed. The bell rang and the 14-year-old, clad in hiking boots and jeans, strode off, leaving yet another vacant seat on the stage.

States News Service contributed to this report.