Nucleation (noun)

1. The formation or generation of a nucleus or nuclei.
2. The process by which a substance comes out of solution and forms a solid, such as a crystal or a precipitate.
3. The process of forming a nucleus, such as a protein or a virus, around which other molecules or particles can collect.

Origin:

From latin nucleus ("kernel, nucleus") + -ation.

Examples:

1. The nucleation of ice crystals in clouds causes snow to fall.
2. Nucleation is a key step in the formation of crystals.
3. The nucleation process of protein aggregation is an important topic in biochemistry.
4. Nucleation is necessary to form a stable liquid droplet.
5. The nucleation of a new phase in the material is a gradual process.