This Latin word was borrowed into English at the beginning of the seventeenth century. In its original language, it meant a garment made of patches, but could also figuratively refer to a literay work that had been created by sticking together bits of the work of other writers, as patchwork recycles older garments.
Both of these senses came into English pretty much together, though the literary one soon triumphed. An example appears in a letter that Oliver Goldsmith wrote to a newspaper in 1767: “He had taken my plan to form the fragments of Shakespeare into a ballad of his own. He then read me his little Cento, if I may so call it, and I highly approved it.”
William Hazlitt created a typically forthright essay, On Familiar Style, which should be required reading for aspiring writers. He deprecated those who favoured style over substance: “Their most ordinary speech is never short of an hyperbole, splendid, imposing, vague, incomprehensible, magniloquent, a cento of sounding common-places.”