In one of my recent language videos (go here to see it) The Deer Hunter shared that Pap always called his billfold his pocketbook. I never thought anything about it because I grew up hearing him say it, but The Deer Hunter says he never heard another man call his billfold a pocketbook.
I found the following on the Online Etymology Dictionary.
also pocket-book, 1610s, originally a small book meant to be carried in one’s pocket, from pocket (n.) + book (n.). Meaning “a flexible booklike leather folder for papers, bills, etc.” is from 1722. Meaning “a woman’s purse” is from 1816.
The entry makes Pap’s usage seem totally normal.
While I knew from The Deer Hunter that Pap’s usage of pocketbook was unusual, I was surprised by how many people commented that their mother always called her purse a pocketbook. I certainly know what a purse is, but I’ve never called my purse anything but a pocketbook. There were so many remarks about ladies calling their purse a pocketbook that I began to wonder if that usage is fading away too. If you carry a purse do you call it a purse or a pocketbook?