Definition of full house
A full house is a full hand. It is also called a full. A full house is a pair plus a three of a kind. If you have AK in hand on A-K-A, we have a full house or a "boat". Full hand, full house, full, boat, full boat, are all synonyms for the same hand. At casino poker tables, you will hear all expressions at an equal frequency. Players who want to show other players that they weren't born yesterday will use "boat" more often than a full hand or full house. The expression gives the impression that you are more erudite than other players, that you know the game better.
Poker is the marine analogy
Boat is not the only term that refers to marine vocabulary. We talk about the turn, the river, a float (when we call a bet with the intention of bluffing on a preflop to come), etc. There are also analogies in relation to the Wild West (a barrel is referred to as a shot when betting, kings preflop are called cowboys, etc). On the other hand, on a poker table, it's always best not to spread our knowledge too much to other players so as not to arouse their mistrust of our skills!