ManyThings.org's Online Word Based Games for ESL students that offer three games: matching, speed games and jigsaw for practice in irregular verbs, homonyms, opposites, time words and cardinal words. In addition this site has a vocabulary section called English Vocabulary Word Lists with Games, Puzzles and Quizzes , which provides word lists and an online activities that use those words. Activities include hangman, scrambled words and matching.
vocabulary.co.il is another great site for enjoyable vocabulary games. The age for this site is K-5th grade and it has a variety of games from audio word matching to crossword puzzles. It includes topics such as the Dotch word list, sight words, suffixes and idioms. It also includes phonics games and some foreign language matching games.
I played the idiom game and match several common phrases from "knock your socks off" to "cream of the crop." I then moved on to word builder, which is a game with blocks of letter that are touching each other and you click on the letters to form any words you see; when you form a word those letter disappear and the letter above drop into their place (like Tetras). The word builders game would be more challenging and for advanced learners or pairs. Although most games where geared toward younger grades the root word meaning match game is designed for high school age students.
This site offers an array of online games to facilitate and reinforce many vocabulary concepts that are being taught in the classroom.