uu-uu
A low, threatening growl from a dog warning you to stay away. Tense and menacing.
💡Approaching a guard dog — 'The dog started uu-uu growling when I got close.'
番犬がうーうーと唸っている。
The guard dog is growling uu-uu.
The dog went ___ and bared its teeth at the stranger.
犬が見知らぬ人に○○と唸りながら歯をむいた。