THESIS: six cells with a downward finish
Start THESIS with T at row 2, column 4. Move left to H at row 2, column 3, up to E at row 1, column 3, then left to S at row 1, column 2. From there, move down to I at row 2, column 2 and down again to the final S at row 3, column 2. Read the six cells as T, H, E, S, I, S. The two Ss occupy separate positions, with I between them in the word.
Think of the movement as left, up, left, down, down. The last two moves stay in one column, with no turn between I and the final S. Overall, you make three turns along four straight segments. The route spans three rows and three columns, visits two edge cells, and touches no corner. Both endpoints have three open orthogonal neighbors on the board. These six distinct cells leave 24 open cells for the other entries.