Definition
Atomic Attribute (Relational Algebra)
An attribute is called atomic if it cannot be appropriately divided into multiple smaller attributes.
Appropriateness
Atomicity does not necessarily mean that attribute which are divisible must be divided at any cost. For example, a date is already atomic whereby it can be divided into day, month and year. The same applies for values, such as addresses. If not necessary due to business rules, the address must not be divided into smaller atomic values.