noun

1. a mass of snow packed together into a ball
2. ☆ any of various plants with snowball-like flowers; esp., a cultivated European cranberry bush (Viburnum opulus var. roseum) with spherical clusters of sterile, white or pinkish flowers

intransitive verb

1. to increase or accumulate rapidly and uncontrollably, like a ball of snow rolling downhill
2. to throw snowballs

transitive verb

1. to throw snowballs at
2. to cause to increase or accumulate rapidly