But, when a word is added to the dictionary as an official English word, you can also use it in written form, for example in your IELTS Writing test.
However, you don’t use slang in formal written work. You can also come across it in SMS or social media. Slang is very informal language or specific words used by a group of people. Usually you’ll hear slang in spoken language. Sometimes even slang, like LOL, makes it into dictionaries as a new English word.
For instance, the latest update of the Oxford English Dictionary added new English words like banana bread, LOL and plant-based. Dentists might use the new word ' amelogenesis ' which means “the formation of tooth enamel by ameloblasts.” For example, some new words are very specific to a particular occupation. So, that doesn’t mean that all the new words in English are widely used in everyday life. The more people use it, the more likely it will be noticed by dictionary editors, or lexicographers, like the people who work at dictionaries like Merriam-Webster or the Oxford English Dictionary. One person uses a word, then others pick it up. New words are used in conversation first. A new English word enters a dictionary when it is used by many people and all these people agree that it means the same thing.