Perpendicular refers to the relationship between two geometric objects that intersect at a right angle (90 degrees). Specifically:

• Two lines are perpendicular if they meet at a point and form four right angles (each 90°) at the intersection. This is often denoted by the symbol "⊥", for example, line lll is perpendicular to line mmm is written as l⊥ml\perp ml⊥m

• Perpendicularity applies not only to lines but also to segments, rays, planes, or a line and a plane, as long as the angle of intersection is 90 degrees

• A perpendicular line to a segment that bisects it into two equal parts is called a perpendicular bisector

• The concept of perpendicularity is fundamental in geometry, used in defining right triangles, calculating shortest distances from points to lines, constructing shapes like squares and rectangles, and in various applications in mathematics, engineering, and architecture

In summary, perpendicular means "at right angles," and two objects are perpendicular if they intersect forming a 90° angle