A directory service from Microsoft Corporation, similar in concept to Novell Netware Directory Services (NDS), that also integrates with the user organisation’s DNS structure and is interoperable with LDAP. Active Directory is included in Windows 2000.
- Active duty
the status of full-time service: on active duty. Contemporary Examples Right now there are only about 2,500 SEALs on active duty in a range of missions worldwide, virtually all of them secret. The Navy SEALs Who Saved the Day Tony Doukopil May 2, 2011 The Army would pay for Kole to complete his undergraduate degree, […]
- Active galactic nucleus
active galactic nucleus active galactic nucleus (āk’tĭv) See under galactic nucleus.
- Active galaxy
noun a galaxy that emits usually large amounts of energy from a very compact central source, such as Seyfert galaxies, radio galaxies, and quasars Also called active galactic nucleus active galaxy A galaxy emitting unusually high quantities of radiation from an active galactic nucleus at its center. Some active galaxies emit more energy in radio […]
- Active hydrogen
. hydrogen in the form of single atoms, rather than molecules, which makes it extremely reactive.