One by one, students from around the city walked to the center of a stage tucked away in the basement of the Boston Public Library in Copley Square.

Some, nearly too short to reach the microphone, stood on the tips of their toes to be heard, their small voices echoing through the auditorium as they spoke each carefully considered letter.

The 21 spelling bee champions from schools across Boston were battling Saturday morning to be crowned the city’s best young speller after taking the title at their respective schools.

Some wore buttoned shirts and ties, while others opted for T-shirts adorned with sparkling designs and logos. Peering out past the three-judge panel, they saw a sea of encouraging faces of parents, grandparents, and siblings, who cheered them on as they tackled words that ranged in difficulty from “shampoo’’ to “nachtmusik.’’

The competitors, all in grades four through seven, were fighting to win the 10th annual Boston Centers for Youth & Families Spelling Bee.

The title — and a trip to the Scripps National Spelling Bee in Washington, D.C., this May — were on the line.

In the minutes before the bee kicked off, parents and contestants gathered outside the Rabb Lecture Hall in the library’s lower level, huddling around cups of coffee, bagels, and pages of practice words stapled together as they snuck in some last-minute preparation.

Attendees soon took their seats, waiting for the spellers to proceed to seats on stage. Wearing placards around their necks with their names, the 21 competitors filed in and took their spots as family members held up phones and cameras, cheering on the group.

“I know you’ve all worked hard to be here representing your school,’’ said Daniel Koh, chief of staff for the city of Boston and a competition judge. “To all the students, remember you are all winners today.’’

Koh, along with Scot Colford, the library’s online and web services manager, and Elizabeth Kurkjian-Henry, a retired Boston public school teacher, served as the judges, reading off the words and providing a definition or language of origin when prompted.

The competition tightened as contestants slipped up on tricky terms like “guillotine’’ and “chary.’’ With each misspelled word, the judges would ding a bell, sending another student off the stage to rejoin his or her parents in the crowd.

After a fierce battle and 14 rounds, only two remained.

Farah Raslan Haniff, a fourth-grader at Winship Elementary School in Brighton, and Mira Yu, a sixth-grader at the Eliot K8 Innovation School in the North End, competed fiercely for 13 more rounds. They spelled “mnemonic,’’ “fuselage,’’ and “Eocene’’ with ease, matching each other in the head-to-head final rounds.

In the 27th round, Mira stumbled over “douane,’’ putting Farah in the position to take first place if she could correctly spell the final word. Sitting in her seat on stage, her feet hovering a few inches above the floor, she was one of the bee’s youngest competitors.

After nearly two hours of competition, Farah stood and took the mike for a final time, angling it down to reach her.

The winning, championship word? Cacophony.

Both girls, along with second runner-up Sylvia O’Hearn, received trophies for placing in the competition.

“I’m speechless,’’ 9-year-old Farah said after winning, a smile plastered across her face as she clutched a large gold trophy to her chest. “Mostly, it was the help of my mom.’’

Farah’s parents helped her to study the words by printing them out and pasting them around their apartment. Originally from Malaysia, the family is here until her father gets a master’s in public administration at The John F. Kennedy School of Government at Harvard this summer. They said she’s always had a great memory, reading books and reciting back what was on each page.

They’ll be off to represent Boston at the national competition, where the winner will take home a $40,000 cash prize.

For Farah’s family, getting the opportunity to compete in the nation’s capital is an opportunity they could never have imagined.

“We are very proud,’’ said Azna Zaini, Farah’s mother, elated by her daughter’s win. “It’s a really good opportunity.’’

Amanda can be reached at amanda.hoover@globe.com. Follow her on Twitter @amahoover.