Both a noun and a verb, referring to someone who lives aboard a boat, e.g., 'They live aboard their boat' or 'he is a live-aboard'. Can be temporary or permanent, for the length of a dive, vacation, season, lifetime or retirement. If of a more permanent nature, refers to someone who likes the carefree lifestyle associated with living on a boat vs. the responsibility of living in a dwelling on land
One to another: My Dad is retiring soon and he's going to sell his house and become a live-aboard.
Another: No way!
One: Yes, he's going to live-aboard his boat and just sail around the Caribbean and see every single island.