to spread over a large area, or (especially of things made of cloth) to become filled with air and appear to be larger

Smoke billowed (out) from the burning building. 滚滚浓烟不断从着火的大楼里涌出。

The sheets/shirts hanging on the line billowed in the breeze. 挂在绳子上的床单／衬衫在微风中飘动。

We watched the boats with their billowing sails. 我们看着那些小船鼓起风帆。