Say you’re reading Lawrence Ferlinghetti’s poem "Americus, Book I," and you get to the second line and already there’s a word you don’t know: "palimpsest." What do you do? Look it up, of course. But you don't need to search through your bookshelves for the answer, instead, online dictionaries offer a convenient place to demystify those puzzling words.

Merriam-Webster’s website, www.m-w.com, can tell you what "palimpsest" means, of course, but the site offers much more than simple definitions. A number of free, interactive features aid visitors in discovering and appreciating language, contemplating etymologies, or just having fun with words. There are word games, audio clips that demonstrate pronunciation, a Word of the Day feature, and free downloads, such as a button for your web browser to look up words in the dictionary or thesaurus instantly from anywhere on the Internet.

There is also a Word for the Wise feature, in which radio host Kathleen Taylor tells fascinating, true stories behind common words and phrases, such as "at your beck and call" and "get your goat." To mark the birthday of Samuel Taylor Colerdige, she did an entire segment on the definition of "poetry," quoting Colerdige's own description and one by the French artist Jean Cocteau, who asserted, "the poet doesn’t invent. He listens."

Kids will enjoy the site as well. Word Central is Merriam-Webster’s award-winning site for younger readers and writers. Whimsically designed, the site features a Daily Buzzword, a Coding Chamber to code or decode messages to friends, and a Verse Composer, where one can fill in the blanks to create original poems. A favorite feature of Word Central is the Build Your Own Dictionary page, where kids can submit their own invented words for the site’s dictionary. One student, for example, coined the new word "Figeturnity," which means "the last five minutes before the bell rings that seem to last forever."