ululate

"When other birds are still, the screech owls take up the strain, like mourning women their ancient u-lu-lu." When Henry David Thoreau used "u-lu-lu" to imitate the cry of screech owls and mourning women in that particular passage from Walden, he was re-enacting the etymology of ululate (a word he likely knew). Ululate descends from the Latin verb ululare. That Latin root carried the same meaning as our modern English word, and it likely originated in the echoes of the rhythmic wailing sound associated with it. Even today, ululate often refers to ritualistic or expressive wailing performed at times of mourning or celebration or used to show approval.