Hook up with Definition 1 of 3Pro Tip 1/3Casual Meetings Used when planning informal gatherings, not formal events. Let's hook up with our classmates for a study session. Pro Tip 2/3Not Always Planned Can refer to spontaneous or last-minute plans to meet. We just decided to hook up with the group downtown. Pro Tip 3/3Common among Youth Frequently used by younger people when talking about socializing. Are you going to hook up with us after the concert?