Browse a website like vocabulary.com/, which has an interactive dictionary and thesaurus that uses visual word maps to make learning vocabulary easier. There are also links to a variety of word and etymological dictionaries and thesauruses.
Sign up on dictionary.com for the word of the day. You'll receive a daily email with a word not commonly known or used in everyday conversation. You can also benefit from the dictionary and thesaurus portion of this website by using it to look up unfamiliar words as you read a newspaper, magazine article or book.
Complete a crossword puzzle online. Several websites offer free online crossword puzzles,. Two reliable ones are dictionary.com and bestcrosswords.com. Doing a crossword from the convenience of your computer lets you review the vocabulary you already know, while it requires your brain to work harder because it uses a brain function called fluency (word finding) that is connected to the language and speech areas of your brain. Make sure to choose a challenging crossword puzzle because your brain won't benefit from an easy one.
Read newspaper articles online. Browse the homepage of your local newspaper or visit the websites of major newspapers such as the Wall Street Journal or the New York Times. As you read through an article, be sure to stop when you come to an unfamiliar word and look it up on an online dictionary.