Also: bob and loco

“Plumbum” sounds like slightly naughty term of affection. It’s not, though; it’s Latin for the element lead. Pliny the Elder named some flowers Plumbago, maybe because the white dust on the leaves reminded him of white lead, a terrific but poisonous pigment. Plumbago is also an archaic word for graphite, which looked like lead ore to the folks who mined it in Seathwaite, England. They first used it to mark sheep, an early pre-subway form of graffiti. But there’s never been any lead in pencils. There’s plenty in water pipes, though, so the folks who fix them are called plumbers.