The full form of tmw is tomorrow
The highly popular abbreviation “tmw” is used in texting and online communication as a shorthand version of the word tomorrow. It simply means the day after today.

Origin of TMW
Specific origin information cannot be found regarding the abbreviation “tmw.” As with most internet slang, origins are typically difficult to track down. However, one can most likely assume that someone was in a hurry one day texting and used this as an abbreviation and it just stuck from there. As more and more people began to see it and use it, the abbreviation was adopted into popular usage.

Other Meanings
Although the most widely accepted meaning of “tmw” is an abbreviation of the word tomorrow, the letters can have some other meanings also. When used as an acronym, “TMW” or “tmw” can mean “that moment when,” “tell me when,” “tell me why.” or many other phrases. These are just four of the most popular after meaning “tomorrow.” Again, you may need to pay attention to the context of the sentence to determine the meaning of “tmw” when used during a conversation.

Example Conversations
An online exchange between two users on Facebook negotiating a meeting time to buy an item.

User 1: I want to buy this!
User 2: Okay, when can you meet.
User 1: I can meet you tmw at 5 pm. Where would you like to meet?
User 2: We will meet at the Walmart parking lot in Camden.
User 1: Awesome! See you there tmw at 5!