Clairvoyant literally means “clear-sighted” in French, and for nearly 200 years that is what it meant in English as well. It wasn’t until the mid-19th century that it took on the meaning of “having psychic gifts” or “seeing beyond” that it carries today.
In the 19th century, the term clairvoyant was widely used in a medical context. An especially astute doctor might be able to see a patient’s symptoms and try to make a “clairvoyant diagnosis.” While some of these doctors were legitimate and extremely skilled, the term “clairvoyant physician” was generally used to describe your typical 19th-century quack.
As the meaning of clairvoyant started to shift, reference books of the time attempted to approximate the new uses of the word. The 1873 edition of The American Cyclopaedia describes a clairvoyant as someone who can see through opaque objects, therefore possessing the power to “read a book unopened, or a letter which is enclosed in a solid wood box.” Today, however, clairvoyant carries more spiritual connotations, and such skills would never be cheapened by freak-show displays like divining the text of an unopened book. Rather, the modern clairvoyant prefers only to “see” things that cannot be easily refuted by disbelieving skeptics.

Did you mean clairvoyant?