“Hip-hop was set out in the dark/ They used to do it out in the park” begins MC Shan’s classic rap track “The Bridge.” But while the almost 30-year-old track refers to rap’s park days in the past ...

“Cipher” refers to either a code—a language known only by adepts, impenetrable to outsiders—or the figure zero. “Cypher,” meanwhile, refers to both a code and a circular shape. The difference is that ...