The term 'Strike Zone Bottom' refers to the area of the strike zone that is located at the bottom of the batter's KNEES. This area is considered to be the most difficult part of the strike zone for a pitcher to hit, as it requires precision and accuracy to hit the target. The crossword solution for this term is 'KNEES', which is an accurate representation of the area of the strike zone that is located at the bottom of the batter's KNEES.