A 13-year-old girl won America's 79th national spelling competition last night, trotting out the letters of "ursprache"- a technical term for language - in front of millions of viewers on primetime television.

Katharine Close, of New Jersey, came out on top after seven rounds of sudden death spelling, competitively forming words like "tmesis" (putting a word in another one), "izzat" (honour) and "kundalini" (life force in your spine), while her last surviving rival, Finola Mei Hwa Hackett, of Alberta, in Canada, hit back with "poiesis" (the act of making), "koine" (common language) and "tutoyer" (using the "tu" form of address in French) .

The decisive moment, in a final that commentators thought was less emotionally fraught than recent years, came when Hackett stumbled over "weltschmerz" (world weariness), erroneously starting with a "v".

Close held her nerve to render "ursprache" and later described her relief when the word was announced.

"I couldn’t believe it. I knew I knew how to spell the word and I was just in shock," said Close, a veteran of five national finals who finished in seventh place last year. "I couldn’t believe I would win."

Close became the first female winner of the Scripps National Spelling Bee since 1999, and the first ever from New Jersey. She took home $42,000 (£22,524) in prize money.

Spelling bees have enjoyed a recent explosion of popularity in America, with books, films and a Broadway musical all spinning off the success of Spellbound, a documentary that followed the finalists of the 2000 competition.

ABC dropped its coverage of Miss America last summer and promoted the Spelling Bee to primetime for the first time.

Despite the anticipation and record size of the competition — 275 spellers from across North America — last night's 20 rounds failed to touch the drama of 2004, when a young competitor called Akshay Buddiga fainted at the microphone before rising to make his way through "alopecoid" (foxlike).

The most controversial moment last night came when Saryn Hooks, a 14-year-old from North Carolina, was knocked out of the competition for her spelling of "hechsher" (sign of kosher approval) but was reinstated when the judges realised that she had in fact spelled it correctly.

"I didn't know the word, and I guessed on it so I just thought I was wrong," Hooks told ABC this morning. She went on to take third place.

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