There are almost 1,000 pictures in the Oxford Advanced Learner's Dictionary and in the Oxford Advanced American Dictionary.
If there is a picture at a dictionary entry, you will see a small version of the picture at the correct part of the entry. For example if you look up butterfly, you can see two of these small pictures, one at the first meaning and one at the second meaning. When you click on or tap any small image, a larger picture will open up, showing a group of related vocabulary items.
The pictures in our learner's dictionaries are a good source of vocabulary because they show lots of related items. The big pictures contain lots of different labels so that you can study other words along with the word you are looking up. For example, the word "butterfly" in English is both the name of an insect and the name of a swimming stroke, and at the entry for butterfly you can see pictures showing a selection of different insects, as well as a picture showing a number of different swimming strokes.
Every dictionary entry that includes a picture is listed in the Pictures wordlist. There are two lists - one for the Oxford Advanced Learner's Dictionary and one for the Oxford Advanced American Dictionary. Simply click on an entry in the list to go to that entry.