Create an account or log in to Instagram - Share what you're into with the people who get you. (Definition of IM from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press) instant messaging (IM), form of text-based communication in which two people participate in a conversation over their computers or smartphones via an Internet -based chat room or application. IMDb is the world's most popular and authoritative source for movie, TV and celebrity content. Find ratings and reviews for the newest movie and TV shows. Get personalized recommendations, and learn where to watch across hundreds of streaming providers. Instant messaging (IM), sometimes also called messaging or texting , consists of computer-based human communication between two users (private messaging) or more (chat room or group ) in real-time, allowing immediate receipt of acknowledgment or reply. The meaning of IM is to send an instant message to. How to use IM in a sentence. IM is short for instant message, a message directly sent from one person to another. IM is also short for Instant Messenger, a program that connects users to the Internet or network to send text messages. (Definition of IM from the Cambridge Advanced Learner's Dictionary & Thesaurus © Cambridge University Press) This disambiguation page lists articles associated with the title IM. If an internal link incorrectly led you here, you may wish to change the link to point directly to the intended article. Originally the Accusative Singular ended in -im, the Ablative Singular in -ī, and the Accusative Plural in -īs; but these endings have been largely displaced by -em, -e, and -ēs, the endings of Consonant-Stems.