gnomon

Everyday

1. The part of a sundial that sticks up and casts the shadow that shows the time. tree →
2. (maths) In geometry, the L-shaped piece left when a smaller shape is cut out of the corner of a larger similar shape, such as a square. tree →

In the lessons

Used in science and history lessons on telling time by the Sun, and in maths puzzles about shapes and patterns. It tells the reader which part throws the shadow. Phrases: the gnomon of a sundial, the shadow of the gnomon.

Examples

• The gnomon casts a shadow on the sundial. tree →
• We made a sundial with a pencil as the gnomon. tree →
• At noon the shadow of the gnomon is shortest. tree →
• The gnomon must point north in the UK. tree →
• In Australia the gnomon of a sundial points south. tree →
• In maths, a gnomon is the L-shape left when you take a small square out of a big one. tree →

Note

Silent g: say NO-mon. Plural gnomons. Do not confuse with gnome (a little garden figure). The gnomon is tilted at the same angle as your latitude so the sundial works all year.