1580s, "like the moon;" 1848, "dreamy, listless," from moon (n.) + -y (2). Cf. moon (v.).
Behaving in a pleasantly listless and dreamy way: in a back booth at Caballero's where Carolyn and I talked and became drunk and moony (1848+)
A member or disciple of the Unification Church
[fr the name of the leader, Sun Myung Moon]