Geometry Words

Visual Geometry Dictionary
for Kids and for Kids' Teachers

Clicking one of the terms below will access a visual display showing one or more individuals' way of understanding the term. We hope you will enjoy seeing our creative ways for making sense of geometry words.

This geometry dictionary is an ongoing project developed by the students at Oklahoma State University in the course MATH 3403 Geometric Structures, a course for prospective elementary teachers.

Lines and Segments:

Parallel Lines Perpendicular Lines Perpendicular Bisector Segment Bisector


Acute Angle Alternate Interior Angles Angle Bisector Complementary Angles
Congruent Angles Corresponding Angles Obtuse Angle Reflex Angle
Right Angle Supplementary Angles Vertical Angles


3-4-5 Triangle 30-60-90 Triangle 45-45-90 Triangle Acute Triangle
Altitude Balance Point Circumcenter & Circumscribed Circle Equilateral Triangle
Incenter & Inscribed Circle Inscribed Triangle Isosceles Right Triangle Isosceles Triangle
Median Obtuse Triangle Perpendicular Bisector of Side Right Triangle, Hypotenuse, & Leg
Scalene Triangle


Adjacent Angles Adjacent Sides Cyclic Quadrilateral Diagonals
Diagonals Bisecting Angles Diamond Inscribed Quadrilateral Isosceles Trapezoid
Kite Line of Symmetry Mutually Bisecting Diagonals Opposite Angles
Opposite Sides Parallelogram Perpendicular Diagonals Quadrilateral
Rectangle Rhombus Square Trapezoid


Convex or Concave Decagon Diagonal Dodecagon
Heptagon Hexagon Inscribed Polygon N-gon
Nonagon Octagon Pentagon Perimeter
Regular Polygon Simple Polygon Vertex


arc, major & minor Center, Diameter, & Radius Chord Sector
semi-circle tangent line

Folding or Reflecting:

Corresponding Points & Lines Hamburger & Hotdog Fold Image Line of Symmetry

Other Terms:

Coincident Congruent Similar Simple Closed Curve

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