• DoD Dictionary -- This is the new, official, Joint Publications 1-02, Department of Defense Dictionary of Military and Associated Terms.  A 606 pg PDF file.

• U.S. Army Abbreviations, Brevity Codes and Acronyms Online -- This online edition has officially replaced the old AR 310-50 per
  AR 25-52.
• FM 101-5-1 (MCRP 5-2A) -- Operational Terms and Graphics
• USAF Acronyms -- Air Force Acronym list
• USAF Acronyms Sensors Directorate
• NAVAIR Weapons Division Acronym List.
• NAWCTSD Acronyms -- Naval Air Warfare Center Training Systems Division
• ADA Glossary -- Focused on Air Defense Artillery terminology.  Includes acronym list.
• MDA Glossary -- Ballistic Missile Defense glossary at the MDA.
• Electronic Warfare -- Space & Electronic Warfare Lexicon
• Aerospace -- Dictionary of Technical Terms for Aerospace Use
• CALL Dictionary and Thesaurus -- The Center for Army Lessons Learned online dictionary and thesaurus.  
• JIST³ --Test & Evaluation Acronym Listing
• Munitions Glossary -- Terminology related to munitions, courtesy of FAS.  See also the References on the Munitions & Missiles page.
• Radar Glossary -- Courtesy of the US Air Force 84th Radar Evaluation Squadron.  They also provide an Acronym List.
• NATO Glossary of Abbreviations
• NATO Glossary of Terms and Definitions
• Defense Acquisition Glossary

See also Business and General References.