A medical dictionary is a lexicon for words used in medicine. The three major medical dictionaries in the United States are Stedman's, Taber's, and Dorland's Pocket Medical Dictionary. Other significant medical dictionaries are distributed by Elsevier, the world's largest publisher of medical and scientific literature, and their French division Masson. Dictionaries often have multiple versions, with content adapted for different user groups. For example Stedman's Concise Medical Dictionary and Dorland's are for general use and allied health care, while the full text editions are reference works used by medical students, doctors, and health professionals. Many of the dictionaries mentioned above are available online, and other electronic dictionaries for medicine are available as downloadable software packages for Apple Macintosh and Windows computers, PDAs, and smartphones or as CD-ROM, as well as bilingual dictionaries and translation dictionaries.