EconPort is a digital library funded by the USA's National Science Foundation. Their glossary takes content from the econterms.org glossary by Peter Meyer and the Sonderforschungsbereich 504 glossary developed at the University of Mannheim. It covers microeconomics, experimental economics and econometrics.
Glossaries of Economic Terms in Intermediate Microeconomics
This is an extensive index of micro aspects of the CyberEconomics on-line textbook written by Roger Schenk. It contains more than a hundred entries linked to appropriate parts of the text, from adjustment process to zero sum game. There is also a link to a version of this list that is grouped by topics.
Short glossary of terms used in New Institutional Economics, compiled by a research institute associated with law-and-economics scholar / Nobel prizewinner Ronald Coase. Entries are short, but each carries references to the academic papers that first established the term within new institutionalism, e.g. Transaction cost, Social Cost, Social Capital, Property Rights.
Sonderforschungsbereich 504 is an interdisciplinary research group combining economists with social psychologists. This glossary provides well-written short articles in English on the basic concepts of economics and econometrics, as well as the psychology of decision making and social judgement. Covers most of the 'heuristics and biases' causing deviations from rational choice, e.g. availability, representativeness, risk aversion, anchoring-and-adjustment. Also covers behavioural finance, game theory, experimental economics, auction theory; and applications to life-cycle savings decisions.