Vocabulary - 2D Shapes

The vocabulary list provided is a comprehensive collection of terms associated with two-dimensional shapes, commonly taught in Key Stage 2 mathematics. The term '2D shape' refers to any shape that has only two dimensions—length and width—and lies flat on a plane. Examples include 'circle', which is a round shape with all points equidistant from the centre, and 'circular', an adjective describing anything in the form of, or resembling, a circle. A 'semi-circle' is a half-circle, formed by cutting a whole circle along the diameter.

Geometric shapes with three straight sides and three angles are known as 'triangles', with the term 'triangular' describing anything shaped like a triangle. A 'square' is a quadrilateral with equal sides and four right angles, while a 'rectangle' is a quadrilateral with opposite sides equal and four right angles, hence the term 'rectangular' to describe something in the shape of a rectangle. Other shapes include a 'star', often with five or more points; a 'pentagon', a five-sided polygon with the adjective 'pentagonal'; a 'hexagon', a six-sided shape, described as 'hexagonal'; and an 'octagon', an eight-sided polygon, which can be termed 'octagonal'. 'Quadrilateral' defines any four-sided polygon, and additional terms like 'horizontal', 'vertical', and 'perpendicular' describe orientations and relationships between lines. 'Parallel' lines are equidistant and never meet, while a 'polygon' is a closed shape with three or more straight sides. The 'centre' refers to the middle point of a shape, and 'diagonal' defines a straight line inside a polygon connecting non-adjacent vertices.