I would simply describe this as the process of making big tables into smaller tables.
The proper definition is that database normalization is a method of reorganising data within tables to reduce the level of dependency. This helps to isolate data so that insertion, deletions and updates in a field can be made into a single table. The relationships between the tables would then propagate this throughout the database.
The goal of normalization is to reduce the amount of data within a table and also to make the data within each table make more sense.