When something is underway, it means that plans or actions are happening now and moving forward. Projects, events, and even conversations can all be underway.
You might hear someone say "The project is underway" which means it's finally started and people are working on it. This could be in a meeting where they're discussing progress, or in an email to colleagues who need to know what's happening next. For example, if you're planning a big event like a wedding, the preparations might be underway even though the main day hasn't arrived yet – the invitations will have gone out, and vendors will already be booked.
A road, track, path, or street for going under another way or obstacle.
In motion, in progress; being done or carried out; on a journey.
