To weep copiously; to cry intensely and for a long time. Lauren wept her heart out at the news of her father's sudden death. What did you say to upset your brother? He's been weeping his heart out upstairs for the last half hour!

To grieve or mourn. The phrase is not limited to death—it can apply to a disappointment as well. I dread the day when I come home by Weeping Cross—my first loss in the battlefield will be too much to take.

Said hyperbolically of one who is deemed so cold and indifferent as to be unable to cry tears. I've never seen Claire show any emotion—in fact, she probably weeps millstones. Why didn't you comfort that poor little girl? Do you weep millstones?

To weep copiously; to cry intensely and for a long time. Everyone wept buckets during the funeral. What did you say to upset your brother? He's been weeping buckets upstairs for the last half hour!