Atomicity has different meanings depending on the context: In chemistry, atomicity is the total number of atoms present in a molecule of an element. For example, oxygen (O2) has atomicity 2 because each molecule consists of two oxygen atoms. Atomicity classifies molecules as monoatomic, diatomic, triatomic, etc., based on how many atoms they contain.

In database systems and computing, atomicity refers to a property of a transaction or operation that ensures it either completes entirely or does not happen at all. This means partial transactions are prevented to avoid data inconsistencies. For example, transferring money between bank accounts is atomic because either both debit and credit actions occur or neither does.

In programming (e.g., Java), atomicity means an operation is indivisible and cannot be seen halfway through by other threads, ensuring consistent and race- condition-free access to shared data.

Thus, atomicity generally conveys the idea of indivisibility, either in terms of atoms in molecules or steps in a computational transaction.