Four-letter answer: ISLE
Trace ISLE through these four cells: 1 at row 4, column 4; 2 at row 3, column 4; 3 at row 3, column 5; 4 at row 2, column 5. The letters read I → S → L → E in path order. Each step is orthogonal, and the trace supplies exactly the four positions required by the first answer length.
From the I at row 4, column 4, move up to the S at row 3, column 4, turn right to the L at row 3, column 5, and turn up to the E at row 2, column 5. That is an up, right, up pattern with two turns and three straight segments. The path spans three rows and two columns, visits two edge cells and no corners, assigns four cells, and leaves 18 open cells for the remaining words.