Among the definitions of a lexicon is "a special vocabulary" and this is the National Ground Water Association's version, which contains more than 2,000 industry terms. The document was created by a task force of industry professionals and contains terms with the most relevancy to the various groundwater professions as to the use, protection, remediation, and management of groundwater. It was first published in 2011 and most recently updated in 2015. While there are regional differences in the use of some terms, the document serves as an ideal collection of the definitions that relate to groundwater and the professionals that work with it