There's a reference to a "noblewoman's bonus" on p 43 of the BotM, but I can't seem to find what it's referring to elsewhere in the text and noblewoman does not seem to be listed in the index. What is this referring to?

It's been a while since I read the BotM, so I'm probably overlooking something obvious, but any help would be much appreciated.

It is in the main rulebook, p. 40.

In short, it is the Chivalric Bonus equivalent for the women (Chaste, Energetic, Honest, Modest, Prudent and Temperate totaling 80+), allowing them to boost the harvest results by one step.