Snowball can be used in a few related ways:

A snowball is a rounded lump of snow packed together by hand, often thrown in play. Making a good snowball requires snow that's wet enough to stick together but not so slushy that it falls apart. Kids have been having snowball fights for as long as there's been snow and people to throw it.

The word also describes something that starts small but grows rapidly as it continues, like a snowball rolling downhill that picks up more snow and gets bigger and bigger. A small rumor can snowball into a huge misunderstanding as each person adds details. One missed homework assignment might snowball into falling behind in a whole class if you don't catch up quickly. A successful bake sale could snowball into an annual fundraising tradition that grows larger each year.

This snowballing effect happens because each stage builds on what came before. When something snowballs out of control, it means the growth has become too fast to stop or manage easily. Understanding how things snowball helps you recognize when small problems need attention before they become big ones, and when small successes can build into major achievements.