Definition
Drawing compass
A drawing compass is a hinged tool for drawing circles or carrying the same distance to another place.
What it means
Put the sharp point where the centre should be. Open the legs to the radius you need. Keep that opening unchanged and swing the pencil leg around. The needle stays put, so every mark is the same distance from the centre.
Remember it
One point stays; the pencil swings.
Example
Open the compass to 4 cm. Place the sharp point at centre C and swing the pencil all the way around without changing the opening. Every point drawn is 4 cm from C, so the circle has radius 4 cm.
Watch for
If the opening changes while the pencil moves, the curve will not be one circle with a fixed radius. A compass can also carry a distance without reading a number.
Common mix-up
A drawing compass makes circles and transfers distances. A navigation compass points toward directions such as north; it is a different tool and sense.
Exact meaning
A drawing compass is a hinged instrument with a sharp point and a pencil or marking point. Keeping the opening fixed lets it draw a circle about a centre or transfer one distance to another place.