i Register
In some senses, moonwort is marked as UK, US. Watch for register when choosing this word.
noun
A small fern, Botrychium lunaria (lesser moonwort); later, any member of the genus.
Moonwort is an herb which they say will open locks, and unshoe such horses as tread upon it.
Lunaria annua (greater moonwort); also known as honesty and annual honesty.