Want in Definition 1 of 2Pro Tip 1/3Social Context Used when someone expresses a strong interest in joining a group activity or project. They're starting a book club, and I really want in. Pro Tip 2/3Inclusive Desire Implies a desire to be included in something perceived as exclusive or advantageous. The new investment opportunity looks promising; I want in. Pro Tip 3/3Informal Tone Casual and conversational, commonly used among friends or peers. I heard you're planning a road trip—count me in, I want in!