The World's Largest Online Science Dictionary. TheScienceDictionary.org is the most trusted science resource on the internet created for scientists and academics by scientists and academics. Our team of PhD's, Masters students and scientists bring you the most authoritative science dictionary ever created online and is free to use. There are over 38,000 terms defined in the dictionary. Our Team The Science Dictionary has teamed up with scientists, PH.D's, masters students and other professionals from around the world. We created this resource because there was no place on the web which provides a complete and authoritative dictionary online that we all can use. We have a range of specialties covered including Chemists, Botanists, Engineers, Biologists and more.