1. Wiktionary
2. Google Dictionary (which you can also add to Google Chrome as an extension)
3. Dictionary.com
4. The Free Dictionary (by Farlex)
5. Merriam-Webster Online (but see also their Britannica (Learner’s) Dictionary)
6. Cambridge Dictionary Online

Dr. Merritt also has a few favorite word-focused websites he can personally recommend…

1. Visuwords — different from almost every dictionary you’ve ever seen!
2. ScienceNews Explores, one of the best science websites for students, has a fantastic Scientists Say: Your Weekly Word feature. Be sure to check it out.
3. For students interested in the history/origin of particular words, Dr. Merritt highly recommends the Online Etymological Dictionary, which also has its own Google Chrome extension.
4. Although words are an important foundation for knowledge and understanding, they can also be a source of pleasure and play. If you’ve never played the NYTimes-hosted Wordle game, then be sure to do so. Forewarning: it can be addictive (but surely there are worse addictions!).