Download Geometry Vocabulary

GEOMETRY VOCABULARY
A Third Grade Unit
CENTIMETER
A metric unit used to measure length.
1 centimeter
LINE SEGMENT
A part of a line. A line segment has two endpoints.
It starts and stops.
LINE
A straight path that goes on forever in both
directions
HORIZONTAL
A line that extends from left to right.
VERTICAL
A line that extends up and down.
PARALLEL LINES
Lines that never intersect or cross.
PERPENDICULAR LINES
Two lines that cross or meet to form right angles or square corners.
PERIMETER
The distance around the outside of a figure.
To find perimeter all of the sides in the shape are added together.
side + side + side = perimeter
4 cm
4 cm
3 cm
4 cm + 4 cm + 3 cm = 11 cm
QUADRILATERAL
A figure with four sides.
ADJACENT SIDES
Two sides that meet at a point. They are next to each other.
They are NOT opposite each other.
a
d
b
c
Sides a and d are adjacent to each other.
Sides a and c are opposite each other.
PARALLELOGRAM
A quadrilateral with both pairs of opposite sides parallel.
Only one set of
opposite lines are
parallel.
RECTANGLE
A parallelogram that has 4 right angles.
Opposite sides are the same length.
4 cm
2 cm
2 cm
4 cm
SQUARE
A special rectangle with four sides of the same length and
four right angles.
3 cm
3 cm
3 cm
3 cm
RHOMBUS
A parallelogram with equal sides.
A rhombus does not have to have right angles but it can.
3 cm
3 cm
3 cm
3 cm
2 cm
2 cm
2 cm
2 cm
4 cm
4 cm
4 cm
4 cm