An incomplete Howell movement when not all the pairs meet. One feature of the three-quarter movement is that there are more stationary pairs than in a full Howell but fewer than in a Mitchell. Another is that it is often possible to have the same number of boards in play (and number of boards per board) no matter how many tables there are.
For example, three-quarter movements exist with nine 3-board rounds for 6, 7 or 8 tables.