Webster's Dictionary Online
See also: Dictionaries (Menu)
Reduce Hunger by Practicing Vocabulary Words - Free Rice.Com
Words Most Often Confused
Spelling Tips - Cuesta Community College
Exercises Based on the Academic Word List (AWL) for College Vocabulary
Latin and Greek Roots & Suffixes - Enhance Your English Vocabulary
www.merriam-webster.com
http://www.freerice.com/index.php
http://en.wikipedia.org/wiki/Commonly_misspelled_words Wikipedia
http://www.davidappleyard.com/english/vocabulary.htm David Appleyard
Eight basic rules and more (Also see menu on left side of web page.)
Exceptions to the Rules
http://www.academicvocabularyexercises.com/
http://www.takeourword.com/theory.html#Roots Take TakeOurWord.Com
http://en.wikipedia.org/wiki/Greek_and_Latin_roots_in_English Wikipedia.Org