Half pattern method: A common method of pressing a conical shape which creates two halves that are then joined.

Half section: The view obtained when the cutting plane goes half way across the object to the centre line. It is used for symmetrical objects (the same either side of the centre line). The cutting plane only removes one quarter of the object.

Hidden features: Hidden features are features of a shape that are not visible.

Hidden lines: These are used to represent hidden features on a drawing.

Hidden outlines: The hidden features of a component are drawn on an engineering drawing using thick dashed lines.

Horizontal: Horizontal refers to the orientation of a line or plane (or thing) that is at right angles to a vertical line. In other words, it is something which is aligned with, or parallel to the horizon.

Horizontally: Horizontally describes something which is aligned with, or parallel to the horizon.

Hydraulically operated: Hydraulically operated means operated or moved by water or other liquids in motion.

Hypotenuse: The hypotenuse is the longest side of a right angled triangle.