Sentence:  Among the nonhuman creatures that peopled rural Europe in the Middle Ages — the fairies, elves, dwarfs, trolls, and <WSD>kobolds</WSD> — there were beneficent female spirits who patronized those households that treated them well. 
Meaning of the word marked with <WSD> tags:  A mischievous elf or goblin, or one connected (and helpful) to a family or household.