Merriam Webster has recently unveiled a Visual Dictionary Online with 6,000 images divided by themes. I learned about it from The Teacher List.
It’s an excellent resource, and it also has “drag-and-drop” games. Unfortunately, it doesn’t have a audio. Because of that, even though it doesn’t have as many words, The Language Guide is still the “go-to” online dictionary for English Language Learners.
Both sites are on my English Themes For Beginners page under Dictionaries.