This reminded me of the dictionary I used to bring when I was still a kid. It was at least two and a half inches thick; hence, it occupied most of my backpack. I hated the times when I had to bring it to school, though, as the nerd that I was before, I also enjoyed it. My friends and I used to challenge ourselves by reciting random words and guessing the meaning of each word. Now I wonder if kids nowadays still know how a dictionary looks like.
Going back to your question, most dictionaries do not only provide the meaning of the word but also the origin, and the date when it was first used. To better understand what the word means, usually it also contains sample sentences along with notes about other instances when the specific word can be used. Moreover, tenses are also provided to guide the readers of the proper usage. For the same purpose, synonyms and antonyms are also given. Hence, using a dictionary is quite a useful tool to increase your vocabulary.