Esme is an inquisitive, motherless girl who grows up spending her time in the Scriptorium, a garden shed where lexicographers compile the Oxford English Dictionary. Surrounded by language, she begins secretly collecting discarded word slips, particularly those relating to women and the lower classes, in a wooden box. Her fascination with these forgotten words drives her to question the biases of the scholarly men around her.

Lizzie is a dedicated maidservant in the Murray household and becomes Esme’s closest childhood companion. Despite being illiterate and restricted by her working-class status, she possesses sharp practical wisdom and a grounded perspective on the world. She acts as a nurturing, maternal presence for Esme, though the strict social division between them frequently complicates their dynamic.

Harry is an editorial assistant working on the first Oxford English Dictionary. He is a gentle, affectionate single father who encourages Esme’s intellectual curiosity and introduces her to the mechanics of lexicography. While he loves his daughter deeply, his immersion in the male-dominated academic world often blinds him to the systemic sexism and practical difficulties she faces as she grows up.

Gareth works as a compositor at the Oxford University Press, where he painstakingly arranges metal type for printing. Unlike the academic scholars in the Scriptorium, his labor is highly physical and artistic. He treats Esme with genuine intellectual respect, recognizing the value of her independent research and challenging her assumptions about blue-collar work.

Tilda is a free-spirited actress and active participant in the women's suffrage movement. Unconstrained by the strict moral expectations of Edwardian society, she introduces Esme to a wider, more radical world beyond Oxford's academic bubble. She is deeply committed to political action and fiercely advocates for women's visibility.

Dr. Murray is the lead lexicographer compiling the Oxford English Dictionary. He commands respect among the scholars and oversees the massive, decades-long project of defining the English language. He strictly adheres to the rule that words must appear in published texts to merit inclusion, a standard that inadvertently excludes the oral language of women and the working class.

Aunt Ditte is a volunteer researcher for the dictionary who works remotely from her home in Bath. She is a highly educated, independent woman who tries to intervene in Esme’s upbringing, believing the girl needs formal schooling and proper guidance. She operates within the academic system but frequently submits controversial words for consideration.

Mr. Crane is an unpleasant editorial assistant who joins the Scriptorium staff. He is highly suspicious of young Esme, viewing her presence in the scholarly workspace as inappropriate and disruptive. He actively tries to bar her from the garden shed and reports her when she attempts to collect discarded paper slips.

Bill is Tilda's younger brother, raised primarily by his sister due to their absent parents. He shares his sister’s involvement in the women's suffrage movement and enjoys a casual, bohemian lifestyle. He spends time with Esme during her visits to the theater and local pubs.

Mabel is a working-class vendor at the Oxford marketplace. She provides Esme with a wealth of colloquial, often derogatory or sexual, slang words that the academic men at the Scriptorium refuse to document. She represents the vibrant, unwritten language of everyday women.

Mr. Dankworth is a lexicographer who joins the dictionary project as an editor. He is highly critical, dismissive, and embodies the pervasive sexism of the academic environment. He frequently invades Esme's workspace, belittles her contributions, and secretly alters the work of other editors.

Aunt Beth is Ditte's sister, who lives with her in Bath. She moves in circles of educated, progressive thinkers and spends her time working on an illicit novel. She provides Esme with a model of female independence and intellectual respect.

Mr. Maling is one of the lexicographers working under Dr. Murray in the garden shed. He is a kindly scholar who takes an interest in Esme, teaching her constructed languages like Esperanto while she observes the men working.

Lily is Harry's deceased wife and Esme's mother. Though she passes away before the primary events of the novel, her absence shapes the lives of both her husband and daughter. Esme physically scars her own hand trying to rescue a paper slip bearing Lily's name from a fireplace.