Webster's New World Children's Dictionary, and its variants, are all highly recommended and popular on Amazon.com. The variants include Merriam-Webster Children's Dictionary, Merriam-Webster's Elementary Dictionary and Merriam-Webster's Intermediate Dictionary.
Webster's New World Children's Dictionary, 2015 hardcover edition, by DK Children Publishing, comes with a CD Rom. This is particularly helpful for the intended readers, children ages 6 to 9, who may need help with the pronunciation of words. The Elementary version serves grades 3 to 5 or ages 8 and up, while the Intermediate level is intended for grades 6 to 8, with approximate ages of 11 to 14. Features that create popularity are the inclusion of current words in use, colored illustrations, clear pronunciation keys and samples on the sides of the pages, which all enhance understanding of the definitions.