The Word of the Day comes from "SECOND PLACE" by Rachel Cusk which is longlisted for the 2021 Booker.
INTEGUMENT
noun
a tough outer protective layer, especially that of an animal or plant. "this chemical compound is found in the integument of the seed"
early 17th century (denoting a covering or coating): from Latin integumentum, from the verb integere, from in- ‘in’ + tegere ‘to cover’.