WASHINGTON (Reuters) - Young contestants in the Scripps National Spelling Bee face off on Wednesday with the new challenge of not only having to spell obscure words correctly, but also knowing what they mean.

A total of 281 spellers, aged 8 to 14 and hailing from all 50 U.S. states, will step onto the stage over the next two days to be quizzed on their knowledge of obscure English words.

Prior winners have triumphed with “xanthosis,” a rare skin disease; “euonym,” a name that seems appropriate to its subject, and “logorrhea,” a disorder whose sufferers are verbose but incomprehensible.

Contestants also come from the District of Columbia, U.S. territories and Defense Department schools around the world, with some contestants coming from the Bahamas, Canada, China, Ghana, Jamaica, Japan and South Korea.

For the first time since it began in 1927, the contest is requiring young spellers in preliminary and semifinal rounds to take a vocabulary test. Organizers say it is part of the Bee’s commitment to deepening contestants’ command of English.

Since 2002, a written or computer spelling test has been a component that, along with onstage spelling, factored in determining which spellers advanced to the semi-finals.

This year, competitors will advance to the semi-finals and finals based on their onstage spelling, as well as computer-based spelling and vocabulary questions. Vocabulary evaluation will count for half of a speller’s overall score.

The Bee is taking place at the Gaylord National Resort and Convention Center in Oxon Hill, Maryland, outside Washington.

The spelling preliminaries on Wednesday follow a computer-based test on Tuesday. The semi-finals and finals take place on Thursday, with the competition to be broadcast by ESPN.

The contestants range from third to eighth graders, with 116 speaking more than one language. The group is 52 percent girls and 48 percent boys, Scripps said on its website, and among this year’s field, math is most often cited as a favorite subject.

Two spellers have siblings who won the national title. Vanya Shivashankar, 11, of Olathe, Kansas, last year’s 10th-place finisher, is following her sister Kavya, who won in 2009.

Ashwin Veeramani, 13, of Cleveland, hopes to follow in the footsteps of his sister Anamika, the 2010 champion.

Last year’s winner was Snigdha Nandipati, a San Diego eighth-grader. Since 1999, 10 of the 14 winners have been Americans of Indian descent, including the last five.