How did Ugg boots get their name?

The name on one of the world's best-known boot brands began as an Australian word that nobody can fully explain.

Sheepskin boots were worn in rural Australia long before they were fashionable. Wikipedia reports them in the 1920s, when shearers reportedly liked them. The Australian National Dictionary, compiled at the Australian National University, finds the name in records from the late 1960s. That evidence suggests surfers made the boots popular.

The dictionary calls the origin unknown. Its best suggestion is that "ugg boot" is an alteration of "ugly boot." The spelling wandered too: ugg, ugh and ug all appear. Green's Dictionary of Slang also derives the word from "ugly." Its earliest citation is older still: "ugh boots" in a 1951 trade listing from Malta.

One maker claims to have coined it. Frank Mortel says he began making the boots in the late 1950s. He says he named them after his wife called the first pair ugly. Wikipedia and Dictionary.com report the claim but do not confirm it, and the 1951 citation predates it.

A second theory looks to the sky. Some accounts link the word to "fug boots," which Wikipedia says Royal Air Force pilots wore in the First World War. Dictionary.com says the word may come from a shortened "flying ugg boots," but presents that as a possibility, not a fact.

One thing it is not is the grunt "ugh." Dictionary.com notes that the interjection of disgust dates to 1837 and says the boots are not named for it.

The trademark fight came later. Shane Stedman registered "UGH-BOOTS" in Australia in 1971. In the United States, Brian Smith and Doug Jensen set up Ugg Imports. In 1995 Smith sold his company, Ugg Holdings, to Deckers Outdoor Corporation for $14.6 million. Deckers registered UGG trademarks in the United States in 1996.

From 1999 Deckers sent cease-and-desist letters to Australian sellers. In a 2006 ruling, IP Australia found that the evidence "overwhelmingly" showed ugg, ugh and ug boots were used interchangeably. The Australian National Dictionary says the term is now generic in Australia. In more than 100 other countries, UGG remains a registered trademark.