noun
roar; monster sound
Onomatopoeic word representing the roar of a monster, dinosaur, or large beast, often used in children's media, games, and comics.
怪獣が「ガオー」と吠えた。
The monster roared, "Gaoo!"
子どもがガオーの真似をして遊んでいる。
The child is playing, imitating a monster's roar.