Definition of "harebrained"

“Now why do I get the feeling we're not talking about the harebrained plan you came up with?” “It wasn't harebrained.” “Did it have you going within twenty feet of a whorehouse at night, unchaperoned?” He knew darn well it did.

2008, Sarah McCarty, Promises Reveal, Penguin

Her getting a parcel from a hare-brained wench at the coaches in St. John Street; her booty made at the fire, and again at Harwich, all give us excelle

1722, Daniel Defoe, Moll Flanders, The Author's Preface