- Amateur Telescope Makers Dictionary
Words in nine languages: English, French, German, Dutch, Portuguese, Spanish, Indonesian, Italian, and Russian. Definitions in English.
- Chemistry & Environmental Dictionary
Provides definitions for technical terms and acronyms, and related articles.
- Dictionary of Algorithms and Data Structures
Dictionary of algorithms, algorithmic techniques, data structures, archetypical problems, and related definitions.
- Dictionary of Units, A
An explanation of the principle systems of units, their history, standards, and conversion factors for changing from one to the other.
- Glossary of Botanical Terms
Interactive glossary of terms relating to botany, gardening, horticulture, and landscape architecture.
- Glossary of Genetic Terms
Created by the National Human Genome Research Institute (NHGRI) to help people without scientific backgrounds understand the terms and concepts used in genetic research.
- Glossary of Satellite Terms
- How Many?
Dictionary of units of measurement with commentaries and explanations of the English Customary, Metric, and International Systems.
- Hypertext Glossary of Genetic Terms
Searchable database of genetic terms with hypertext cross references and pictures.
- Lexicon EncycloBio
Provides biological terms, definitions with pictures, and Flash movies. Includes an internal search engine.
- Mathematical Programming Glossary
Glossary of terms (plus supplements) used in optimization.
- Maths Dictionary for Kids, A
Easy definitions for basic math.
- Plasma Dictionary
Database of plasma physics terms.