Aviation Definitions

From Pilots Almanac

FAA Glossary of Aviation Acronyms

FAA Pilot/Controller Glossary - Improved hypertext frontend

Aviation Terms Glossary

United States Aeronautical Contractions

METAR/TAF Abbreviations

American Meteorological Society Glossary

NOAA Weather Glossary

Encylopedia Astronautica

AOPA Aviation Glossary (.pdf)