If this reminds you of the inarticulate cry of disgust that most often appears as ugh! then you’re on the mark. The conventional spelling of ugh! was probably influenced by that of ugsome, something loathsome or horrible. In a case of linguistic turn-and-turn-about, ugsome derives from the ancient and long defunct word ug, which about a millennium ago came into English from the Old Norse ugga, to dread. That Old Norse word is also the source of ugly (which meant frightful or horrible before it weakened to refer to something merely unpleasing in appearance). You could argue that ugsome is the opposite of handsome.
In the centuries before Shakespeare, ugsome was common enough, mostly in Scotland and northern England, but then almost completely died out except in dialect. It was resurrected in the eighteenth century by writers seeking an archaic word to help set a historical scene. The following century, popular authors such as Sir Walter Scott (“Like an auld dog that trails its useless ugsome carcass into some bush or bracken”), Sir Edward Bulwer-Lytton (“‘’Tis an ugsome bit of road!’ said the Corporal, looking round him”) and Charles Dickens (“One very ugsome devil with goggling eyes, seems to hold up frightful claws, to bar the traveller’s way”) regained it some small exposure, though it was never very popular.
Today, ugsome is unknown to most English-speaking people. This is a rare modern example:
The link between motorists and rats may not be immediately obvious — except to that tiny proportion of the population for which car-users are pests and their vehicles ugsome — but drivers and rats both react badly to the stress brought on by crowded conditions.
Yorkshire Post, 6 Sep. 2004.