The Grammarphobia Blog

Muggy waters

Q: The weather forecast in Iowa City is for warm and muggy followed by the arrival  of … hot weather. We are wondering where the term “muggy” comes from.

A: There’s only one good thing we can say about “muggy”—it’s appropriate. It’s a dank and oppressive word for dank and oppressive weather.

The definition in the Oxford English Dictionary sums up “muggy” pretty well: “extremely humid; (unpleasantly) close and warm.”

“Muggy” probably has its origins in an obscure old verb, “mug,” meaning to drizzle or lightly rain.

The verb dates back to around 1400, the OED says, when it appeared in Sir Gawain and the Green Knight. Translated into modern terms, the citation reads: “Mist mugged on the moor.”

An equally obscure English noun, “mug,” dating from the early 1700s, means a mist or fog or drizzle as well as a dull, damp, or gloomy atmosphere.

Both forms of “mug,” the verb and the later noun, have their roots in early Scandinavian and are still heard as regionalisms in parts of Scotland and England.

The OED suggests that ultimately they came from the same Germanic root as “muck”—which also seems appropriate!

But getting back to “muggy,” it first showed up, according to OED citations, in the papers of White Kennett, a historian and bishop of Peterborough who lived from 1660 to 1728.

The bishop kept a manuscript collection of provincial words in which he wrote: “In Kent we call close cloudy hot weather, muggy weather.”

Before people used “muggy,” they might have used “muggish,” an adjective first recorded in 1655 and meaning damp and musty.

In A Dictionary of the English Language (1755), Samuel Johnson defined “muggy” as meaning “moist; damp; mouldy.”

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