Women bonded by a shared political goal; comrades.
'Sisters, thank you for joining the fight.'
Tilda Taylor, 1906
It's a fascinating idea to build a novel around. I'm sure I've read somewhere (though I can't track it down) about some countries or cultures where women do have a complete and separate parallel language -- maybe that's true, maybe it isn't. But it's definitely true, or was true a hundred years ago, that women use language differently, that they have their own experiences of life that demand their own words to describe them.
The process of compiling the dictionary turned out to be a much bigger project than anyone anticipated when it was begun, which means that the story of Esme's life, which runs alongside the gestation of the dictionary, moves quite slowly, though it's a thought-provoking and enjoyable journey. (I definitely enjoyed this novel a lot more than The Surgeon of Crowthorne, perhaps the most famous book about the making of the Oxford dictionary but one I found too long and unexpectedly dull.)