More than 840 words were added to the Merriam-Webster dictionary, including slang words "Instagramming", "bougie", "TL;DR", and "adorbs".
A post announcing the new additions was made on the Merriam-Webster Facebook page on Tuesday (Sept 4), as well as the dictionary's website.
Explaining the additions, Merriam-Webster said: "It's important to remember that new words are added to the dictionary only when they have already been used by many people - often initially by specialists or subcultures.
"Then, gradually, a word's use spreads to the rest of us... The dictionary's job is to report that usage as it enters the general vocabulary."
Bougie is defined as an "informal, usually disparaging" adjective which refers to being "marked by a concern for wealth, possessions, and respectability".
On the other hand, an individual could be called adorbs if they are "extremely charming or appealing".
TL;DR, short for "too long; didn't read", could either be used to say that something would require too much time to read, or be "a briefly expressed main point or key message that summarises a longer discussion or explanation".
Merriam-Webster also acknowledged that different users would have different levels of familiarity with the new words.
"For each reader, some of the new words inevitably seem already familiar, but others will be encountered for the first time in an announcement like this - which probably means we're doing it just about right," it said.
Not all the new additions are millennial slang, either. Some reflect the changing technological landscape in today's world.
These include, "biohacking", referring to "biological experimentation done to improve the qualities or capabilities of living organisms" and "fintech", defined as "products and companies that employ newly developed digital and online technologies in the banking and financial services industries".
Others are indicative of increased interactions between cultures globally, such as "iftar", the meal taken by Muslims at sundown to break the daily fast during Ramadan, and "gochujang", a Korean chilli paste.
Contemporary terms for identities were also added to the dictionary, including "Generation Z" for people born in the late 1990s and early 2000s and "Latinx", a gender-neutral alternative to Latina and Latino.
Merriam-Webster said: "The addition of new words to a dictionary is a step in the continuous process of recording our ever-expanding language."