When you have a good level of English and are able to communicate in different situations, you start to face a new challenge: increasing your vocabulary. One of the best way to do this is to learn synonyms for words you already know. A synonym is a different word that means the same thing. For example, you probably know the adjective fast. Quick and rapid are synonyms for fast. If you already know fast, why do you need to know other words that mean the same thing? For three reasons: 1. to be able to understand what you hear and read, 2. so you don't have to use the same words all the time, and 3. because it's fun. Maybe the first reason is the most important for you, but I would recommend thinking about the second and third as well. Learning synonyms is a great way to rapidly increase your English fluency. A good way to learn synonyms is to use a thesaurus. Here's one online thesaurus for you to try. If you keep a vocabulary file or notebook, making groups of synonyms can be a good way to learn and remember them. In the image here, we have a word cloud of synonyms for nice, which was created with Wordle.