Snowballing can refer to different things depending on the context. Here are some of the most common meanings:

• Behavior: Snowballing can refer to a situation that rapidly gets out of control, as when a snowball grows larger while rolling downhill.
• Sexual practice: Snowballing can refer to the act of spitting semen into a partners mouth after oral sex.
• Economy: Snowballing can refer to a situation in which the exercise of stop orders in a declining market or advancing market or specific share creates further downward or upward pressure, triggering more stop orders, magnifying the decline or advance.
• Science and engineering: In social science research, snowball sampling, or "snowballing," is a technique for developing a research sample. It is a recruitment technique in which research participants are asked to assist researchers in identifying other potential subjects. In chemical and industrial engineering, snowballing is the second and last phase, after aggregation, of the pelletization process.
• Other uses: Snowballing can also refer to the throwing of snowballs, a PvP element in the winter event of the online role-playing game series Guild Wars, and a French silent film from 1896 called Bataille de boules de neige.

In general, snowballing refers to something that grows rapidly out of control or increases at an accelerating rate.