Testament
An older legal term that originally referred specifically to personal property disposition. Today, 'last will and testament' is used as a single phrase meaning the same thing as a will.
Legal Definition
Historically, a testamentary instrument disposing of personal property, as distinguished from a 'will' which disposed of real property. The distinction is now obsolete in most jurisdictions.
Practical Example
When a lawyer drafts your 'Last Will and Testament,' both words together simply mean your will. The term 'testament' alone is rarely used in modern practice.