Vocabulary of art

BASIC GEOMETRY CONCEPTS AND DEFINITIONS

Geometry: it is an area of knowledge which studies any elements and operations on  the plane  such as points, lines or shapes. It comes from the Greek geo "earh" , metry "measurement".
Point: in geometry a point can be defined as the place or location where two lines intersect. A point has no dimensions, no height and no width.
Line: a one-dimensional object formed of infinite points. It has no end points and continues on forever in a plane.
Ray: a line which begins at a particular point (called the endpoint) and extends endlessly in one direction.
End point: an End Point is a point at which a line segment or a ray ends or starts.
Midpoint: it is the point that is halfway between the endpoints of the line segment.
Line segment:  it is a line with two endpoints.
Straight line: a line whose points follow the same direction.
Plane: it is a two-dimensional (height and width) surface. In the space a plane can be defined by two parallel lines, two intersecting lines or one point and a straight line.
Length: measurement of something from end to end.

GEOMETRY DRAWING AND SUPPLIES CONCEPTS AND DEFINITIONS

Freehand: drawn by  hand without guiding instruments, measurements.
Line/Technical drawing: it is a drawing made with the help of supplies. It is usually the kind of drawing used for architecture or enginering plans.
Compass: it is a tool for drawing circles and arcs and also for measuring distances between points, consisting of two arms linked by a hinge.
Protractor: an instrument for measuring or drawing angles on paper, usually a flat semicircular transparent plastic sheet graduated in degrees.
Set squares (UK) triangles (US): they are two special rulers with a triangular shape. One is called the 45º triangle (45º square, UK) and other the 30/60º triangle. Both have the 90º angle. So, they are used to draw certain angles and also to draw parallel lines.
Eraser (Rubber, UK): an object, such as a piece of rubber, used for deleting something.
Marker (felt-tip pen, UK): a pen having a writing point made from pressed fires.
Ruler: an instrument used to draw straight lines. Also called straight edge.