AN ON LINE DICTIONARY - WORDNICK
http://www.wordnik.com/
Type in a word you don't know and you'll not only get a definition, but examples of how the word is used in various formats. Teach your students to use this tool and you'll help them in all forms of learning.

DICTIONARY.COM/TRANSLATOR
https://www.dictionary.com/
From the website: “Dictionary.com is the world's leading online source for definitions, word origins, and a whole lot more. From Word of the Day to the stories behind today's slang, Dictionary.com unlocks the secrets of the English language for millions of people.“

EDUPEDIA - DIGITAL ENCYCLOPEDIA/GLOSSARY/DICTIONARY HYBRID
https://www.theedadvocate.org/edupedia/all-categories/
Found this description on Twitter: "Edupedia is a digital encyclopedia/glossary/dictionary hybrid that serves as an authoritative resource for knowledge and information about teaching and learning." The site provides brief definitions of a wide range of education and learning related topics. 

ENCYCLOPEDIA BRITANNICA
https://www.britannica.com/
Encyclopedia Britannica on line. There may be a subscription fee for use of some features on the site.

ENCYCLOPEDIA OF CHICAGO
http://www.encyclopedia.chicagohistory.org/pages/700025.html
The Electronic Encyclopedia of Chicago is edited by Chicago Historical Society. It is a dynamic and unprecedented metropolitan history. Thousands of historical resources-including articles, photos, maps, broadsides and newspapers-related to Chicago's colorful and complex history are at your fingertips.

ENCYCLOPEDIA.COM - FREE ACCESS
https://www.encyclopedia.com/
From the web site:  "At Encyclopedia.com, you get free access to nearly 200,000 reference entries from sources you can cite. Plus, more than 50,000 topic summaries feature related pictures, videos, topic summaries, and newspaper and magazine articles from around the world. Encyclopedia.com also provides innovative tools that allow you to rate and sort the reference content you find to be the most useful."

THE FREE DICTIONARY. INCLUDES THESAURUS
https://www.freethesaurus.com/
From the web site: "Free Thesaurus is a comprehensive online thesaurus of synonyms, antonyms, and related words. The thesaurus contains more than 145,800 unique entries from three top sources: Collins Thesaurus of the English Language - Complete and Unabridged, The American Heritage Roget's Thesaurus, and WordNet."

LEXIPEDIA - MAKING MEANING OF WORDS
https://www.lexipedia.com/
Type in a word and a splatter map shows numerous variations of that word. Great for expanding vocabulary.

MERRIAM-WEBSTER COLLEGIATE DICTIONARY AND THESAURUS
https://www.merriam-webster.com/
Includes dictionary and thesaurus and word games.

VISUWORDS-™ - A MODERN DICTIONARY FOR A MODERN WORLD
https://visuwords.com/
The best way to understand what Visuwords™ offers is to go to the site and use it. On the home page it says it's "Not  your grand dad's dictionary. It represents Language visually."

WORDSMYTH - DICTIONARY WITH A COMPLETE, INTEGRATED THESAURUS
https://www.wordsmyth.net/
On the home page enter a word that you are looking up in the search box and it will appear on a list of choices. Click the word and a screen will appear with information about that word.