Alla Prima
Alla prima are two Italian words that we use in English to refer to wet into wet painting or a painting made all at once. Often oil paint is used for alla prima painting as it cures slower and has a longer working time. Alla prima painting is in contrast to a painting made in layers, where one allows each layer to dry and then paints another layer on top (often called a staged painting). En plein air painting is alla prima landscape painting done outdoors. But alla prima painting can be done anywhere and is used for portraits, still-lives, and landscapes. Alla prima literally means "at first attempt" in Italian.
Van Gogh primarily worked alla prima as do contemporary painters Carol Marine and Hester Berry.
If you are interested in staged paintings, imprimatura is the first stage of a staged painting.