Meh, it comes up more often than you think. There's a whole Wikipedia page about it's "controversial" use even. I doubt it's as unknown to the general populous as you think.
I knew the word but didn't know what it meant until I looked it up after seeing this. I think I assumed it had something to do with the word we're all skirting around (makes me sound like I have to try to not say it - ugh) but it's from the middle ages and means "stingy", if anyone wants to know.
Older books have it pretty frequently. And gay for happy. And removed for OP bundle of sticks. And so on. Pretty funny reading some of that stuff these days.
If you've never seen anybody use the word, just wait. It'll happen eventually.
Someone in your local-level politics (a city councilman, someone on a university board, etc) or your place of employment will whip that word out, and facepalming will ensue.
It'll be a white guy in his fifties. He'll say that shit in a public setting. People will be like "WTF, man." And then he'll be like "ACKSHUALLY, Niggardly (noun: niggard) is an adjective meaning 'stingy' or 'miserly'. Niggard (14th C) is derived from the Middle English word meaning 'stingy,' nigon, which is probably derived from two other words also meaning 'stingy,' namely, Old Norse hnǫggr and Old English hnēaw."
And he will be genuinely surprised when people don't treat him as a hero.