滚雪球

滚雪球

Literally means:

roll a snowball;grow bigger.

Actually means:

It literally means when a small snowball rolls in the snow, it will grow bigger into a huge ball.

It figuratively means things develop gradually and will grow into bigger number or size.

一个小雪团在雪地里滚动，越滚越大，变成了大雪球。这就叫滚雪球。

滚雪球，比喻事物逐步发展，越来越多，或越来越大。