Definition
Half turn
A half turn rotates something through half a full circle: 180 degrees.
What it means
Picture an arrow attached to a pin. Swing it halfway around an invisible circle, keeping the pin fixed. An arrow that started by pointing right ends by pointing left. You may turn clockwise or anticlockwise; a half turn reaches the same final direction either way.
Remember it
Halfway around means opposite: right becomes left, and up becomes down.
Example
A toy robot faces north. It makes a half turn. North and south are opposite directions, so the robot now faces south. The turn measured 180°.
Watch for
Sliding an object straight across is not a half turn. In a turn, the object rotates around a fixed centre and keeps the same distance from that centre.
Common mix-up
“Half turn” does not mean half of the object. It means half of one complete turn.
Exact meaning
A half turn is a rotation of 180° about a fixed centre. Every point stays the same distance from the centre, and the object finishes facing the opposite direction.