Underway is a term used to describe an activity that has already started and is in progress. ASEA, with 4 letters, is an alternative way of saying 'at sea', which is the phrase used to describe a vessel that is travelling on the ocean. BEGUN, with 5 letters, is another way of saying that something has started. AFOOT, with 5 letters, is a phrase used to describe something that is happening or about to happen. Finally, Goingon, with 7 letters, is a phrase used to describe an activity that is currently in progress.