The crossword solution for the term 'Geometry Topic' is 'AREA, ' which is a four-letter word. AREA is a fundamental concept in geometry, which is the study of shapes and sizes of two-dimensional figures and three-dimensional objects. It is the measure of the size of a surface or region, and is usually expressed in square units. AREA is an important concept in mathematics, and is used to calculate the size of various shapes and figures.