fabulous night bird, chimera
鵺 refers to a mythical creature from Japanese folklore: a chimera-like night bird with a haunting cry. The meanings center on this legendary monster.
鵺 is a Japanese kokuji (国字) combining 夜 (night) and 鳥 (bird) to represent the mythical nue, a creature associated with nighttime and a bird-like form.
A bird (鳥) that appears at night (夜): the eerie, chimera-like nue crying in the darkness.
For コウ, imagine the nue's cry echoing through the night: a hollow, ghostly 'kohhh' sound. Koh -> コウ.