Language Matters | Where the word pox comes from, its derivatives monkeypox, chickenpox and smallpox, and why syphilis was called the pox

The word “pox” has great currency these days, with the global spread of monkeypox. In its acronym, MPX, the last two letters represent the consonants in “pox”.

The word, however, has its origins as an alternative spelling of pocks, plural of pock, referring to a pustule, vesicle, blister or ulcer. The word ultimately originates in the Proto-Germanic *puh (h) – meaning “to swell up, blow up”. This underwent various spelling changes: poc in Old English, pok, poke or pocke through to Middle English, and settling on pock from the 1500s.

Later, pock came to refer especially to pustules typical of chickenpox and smallpox, or the scar they left behind, a pockmark. The plural form pockes/pokkes in late-14th century Middle English, referring to the disease, is said to have been the source of the late-15th-century spelling pox.

Pox came to be used specifically for syphilis, a bacterial infection that starts as painless sores, typically on the genitals, rectum or mouth. This was frequently accompanied by a preceding modifier. In the early 16th century, syphilis was called French pox, because its first European outbreak in the 1490s, in Naples, Italy, was claimed to have been spread by invading French troops.

As it was one of the largest public health burdens in the 16th to 19th centuries, it was also described as “the foule, and contagious Disease of the Great Pox”. Consequently, what we call smallpox, the disease caused by the variola major virus involving skin eruptions that leave cratered pockmarks, was first so named in 16th-century Britain, to distinguish it from the great pox.