Glossaries of Economic Terms

Introductory

Principles (General) Principles of Macroeconomics
Principles of Microeconomics Applied Economics
Statistics for Economists  

Intermediate

Intermediate Microeconomics Intermediate Macroeconomics
Agricultural Economics Development Economics
Econometrics Environmental and Transport Economics
Experimental Economics Financial Economics
Game Theory International Economics
Law and Economics Political Economy
Structural and Institutional Economics
Latest Addition:
Guardian
Economics and business dictionary from The Guardian, with bias towards business and finance but covering main economics concepts (e.g. Deflation, Keynesian economics, Retail price index)) and institutional terms (e.g. Agenda 21, Federal Reserve Board, Nikkei 225). Basic, single-paragraph definitions.