The Dictionary of Chemical Names and Synonyms reduces the amount of time spent identifying a chemical by one of its many common names, synonyms, Chemical Abstracts Service (CAS) number, or simplified molecular input line entry specification (SMILES) notation. The software contains more than 25,000 chemicals and 150,000 synonyms, representing an increase of more than 4,000 and 20,000, respectively, since the last revision. The dictionary features full-text searching and dynamic indices for rapid identification of chemicals.