It's the first time the word has made it into a major dictionary, two Scottish newspapers report.
But its meaning has been extended to also mean a clumsy person or someone who can't pick up a particular skill easily - like computing.
The draft definition according to the dictionary's website says:
Muggle: invented by JK (Joanne Kathleen) Rowling (b. 1965), British author of children's fantasy fiction (see quot. 1997).
In the fiction of JK Rowling: a person who possesses no magical powers. Hence in allusive and extended uses: a person who lacks a particular skill or skills, or who is regarded as inferior in some way.
JK meets a muggle
The dictionary is being updated for only the third time in 146 years. It's quite unusual for a living fiction writer to have one of their words included.
But an OED spokesperson told the Scotland on Sunday newspaper they included "muggle" because it was being used everyday by so many people all over the world.