Glossary of Investigation Terms and Legal Definitions

This collection of investigation definitions is intended to help private investigators, police officers and everyday citizens understand the meaning of various legal terms used by lawyers, attorneys, government officials, law enforcement departments, and other legal professionals.


Why These Terms are Important

During the course of their work, detectives will have interactions with police officers to discuss information contained in police reports; with attorneys and lawyers to discuss court cases and court records; and experts and specialists about such things as forensics, crime scene investigations and even handwriting analysis.

Having an understanding of the legal terms and the definitions will help private investigators “speak the language” of their craft. The more well-versed you become in the language of law, the more valuable you will become to your clients. Being able to translate legalese will help your clients feel more comfortable with you as a true expert investigator and you’ll be able to help guide them through the complexities of the legal system. It’s not your job to take the place of a qualified attorney, but you should be able to “talk the talk”.

List of Legal Terms and Definitions

Following is a list of some of the more commonly used terms and definitions. Click on a term in the list below to view the definition and recommendations for additional resources related to the term.

Our list of private investigation and legal terms is constantly growing, so please check back often. If you have a suggestion for a new definition, or have a question, please send us an email and we’ll do what we can to help.

Related Information

  • Also, see our list of Acronyms related to the legal field, law enforcement and the investigation industry.



Online Dictionaries and Glossaries for Research

Private investigators spend a large proportion of their time conducting research, both in the physical sense and in searching for information and data.  Understanding the origin, meaning and pronunciation of words will help you become more adept at conducting research.

That is where online dictionaries and glossaries come in handy. Online dictionaries and glossaries are designed to make it easy to quickly look up words, find the meaning, associated words, synonyms, antonyms, rhyming words, and more more. Nearly everything there is to know about a word, it’s origin and history is available via a quick online search. Also, many of the more popular sites have software apps that put the data right at your fingertips.

Following are online dictionaries and glossaries for looking up words, acronyms, abbreviations and more.

  • Acronym Finder – The Acronym Finder is a searchable database of more than 369,000 abbreviations and acronyms about computers, technology, telecommunications, and military acronyms and abbreviations.
  • CEO Express – Executive Gateway to the Internet. Provides a large number of categorized links to a wide variety of resources.
  • Dictionary: One Look – One Look dictionary search tool. Use this tool to find the meaning of words.
  • Information Please – Information Please is part of Pearson Education, the largest educational publisher in the world and owner of Prentice Hall, Scott Foresman, Addison Wesley Longman, and other distinguished imprints. Pearson also owns Athe Financial Times and Penguin Putnam publishers.
  • Internet Library for Librarians – Internet Library for Librarians provides links to more than 4,000 resources. All the resources are recommended, selected, and reviewed by librarians. Each entry has a full description of the goals and /or scope of the resource, as well as the contact information if provided. Internet Library for Librarians is a handy and useful tool for both novices and experienced library staff.
  • Investopedia – Investopedia investment dictionary provides the definitions of thousands of financial, investment and banking terms.
  • Investor Words – Launched in 1999, InvestorWords is the premier financial glossary on the web, helping millions of individuals understand and keep up-to-date with the terms that they need to know in order to succeed in today’s financial world.
  • Marketing Dictionary – Internet marketing reference and index of the best sites & articles
  • Medical Dictionary – MedTerms medical dictionary is the medical reference for MedicineNet.com. Our doctors define difficult medical language in easy-to-understand explanations of over 16,000 medical terms. Medterms online medical dictionary provides quick access to hard-to-spell and often misspelled medical definitions through an extensive alphabetical listing.
  • Merriam-Webster Dictionary – Merriam-Webster is America’s foremost publisher of language-related reference works. The company publishes a diverse array of print and electronic products, including Merriam-Webster’s Collegiate® Dictionary, Eleventh Edition—America’s best-selling desk dictionary—and Webster’s Third New International Dictionary, Unabridged.
  • Resource Centers – Library of Congress research and reference information.  The Library of Congress is the nation’s oldest federal cultural institution and serves as the research arm of Congress. It is also the largest library in the world, with millions of books, recordings, photographs, maps and manuscripts in its collections.
  • Technical Dictionary – whatis.com® is a knowledge exploration and self-education tool about information technology, especially about the Internet and computers. It contains over 4,500 individual encyclopedic definition/topics, a number of “Fast Reference” pages and learning tools. The topics contain about 12,000 hyperlinked cross-references between definition-topics and to other sites for further information. The site is constantly updated.
  • Thesaurus – Thesaurus.com is produced by Lexico Publishing Group, a leading provider of language reference products and services on the Internet.  To use the thesaurus, simply type a word in the gold search box and click the ‘Search’ button. A list of synonyms and antonyms will be returned.
  • Webopedia – The only online dictionary and search engine you need for computer and Internet technology definitions.
  • Your Dictionary – yourDictionary.com is a language products and services company that maintains the most comprehensive and authoritative language portal on the web with more than 2500 dictionaries and grammars in over 300 languages, games that build language skills, and a forum (The Agora) for discussing language issues with the logophile community.