Aad

AAD is an acronym with several meanings across different domains, including technology, medicine, and statistics. The exact meaning depends on the context.

Azure Active Directory (Azure AD) is a cloud-based identity and access management service from Microsoft, part of Microsoft Entra. It provides authentication, single sign-on, multi-factor authentication, conditional access, and integration with Windows, Office 365, and thousands of third‑party apps. It is used to manage user identities and access for cloud, on‑premises, and hybrid environments.

Azure AD is not a direct replacement for on‑premises Active Directory. Many organizations use both, with synchronization between them via tools such as Azure AD Connect. Azure AD also supports business-to-business collaboration and business-to-consumer identities, expanding identity management across cloud and external users.

In medicine, AAD can denote acute aortic dissection, a life‑threatening condition caused by a tear in the aorta wall that allows blood to separate the layers. It presents with sudden severe chest or back pain and may be associated with hypertension or pulse deficits. Diagnosis is urgent and typically relies on imaging. Management is type dependent: surgical repair is common for type A dissections, while type B may be managed medically or with intervention if complications arise.

In statistics, AAD can stand for average absolute deviation, the mean of the absolute deviations of observations from the data’s mean. It is a dispersion measure that, in some contexts, is more robust to outliers than the standard deviation.