A troll is a fearsome member of a mythical anthropomorph race from Scandinavia. Their role ranges from fiendish giants – similar to the ogres of England (also called Trolls at times, see Troller's Gill) – to a devious, more human-like folk of the wilderness, living underground in hills, caves or mounds. Source.
Stupid, primitive, distrustful, and unbelievably ugly creatures. They have noses like cucumbers, and a tail. They are horribly strong and fast, and they stink. They often keep boxes full of stolen money and jewels, with which they play for hours, running their fingers through them. Source: Gnomes 30th Anniversary Edition
These trolls have a human-like appearance. Sometimes they had a tail hidden in their clothing, but even that is not a definite. Many of these trolls had a single lock of hair that no human could comb, whereas the rest was generally messy. A frequent way of telling a human-looking troll in folklore is to look at what it is wearing: Troll women in particular were often too elegantly dressed to be human women moving around in the forest. They could attract human males to do their bidding, or simply as mates or pets. Later these would be found wandering, decades later, with no memory of what had happened to them in a troll woman's care. Source.