Designed to provide users with each word's "meanings, usage, pronunciation, grammatical provenance, and syllabication," dictionaries serve one primary purpose, provide definitions (Cassell 121).
The dictionaries listed below are considered subject dictionaries (Cassell 132). They focus on a particular subject area, such as nursing, epidemiology, or public health, and provide definitions through the lens of that particularly field of study. Though you may be able to look up the definition of a particular word in a general dictionary, subject dictionaries provide a more in-depth definition, are more reliable as they are created by specialists in the field, tend to be more current, and "complete gaps in coverage for relatively smaller fields" (Cassell 132).
Dictionaries are arranged alphabetically by term so knowing what word you are searching for aids in the usefulness of this resource.
Cassell, Kay Ann, and Uma Hiremath. Reference and Information Services. American Library Association, 2013.