What word is Akeelah unable to spell during the school spelling bee?

In the movie "Akeelah and the Bee," Akeelah is unable to spell the Word "pneumonoultramicroscopicsilicovolcanoconiOSis" during the school spelling bee. This long and complex Word refers to a type of lung disease caused by inhaling fine silicate or quartz dust. Her struggle with this Word highlights her challenges and the pressures she faces in the competition.