The Dictionary of Lost Words is the story of Esme Nicoll who lives with her single dad, Harry, in Oxford. Harry is a lexicographer working on the Oxford Dictionary (begun in 1879, not finished until 1928). Esme hangs out in the Scriptorium where Harry works; she collects and hides words she finds offensive and as she grows up, she collects words used by women that others find offensive.
There is an important orphan character who features throughout The Dictionary of Lost Words. Lizzy Lester has been a domestic servant since she was 11 when her mother died and her many siblings disappeared. She's 8 years older than Esme and often looks after her for Harry. Eventually, the women become friends. There's a story of adoption too.