Definition Of Form

Form Definition:

Form is the visible shape or configuration of an object, it is the particular way it appears. Shading helps contribute to form.

Adjectives & Synonms for 'Form':

• Shape
• Design
• Layout
• Format
• Outline
• Exterior
• Appearance
• Arrangement
• Construction
• Structure
• Formation
• Configuration

I like this image of the pool balls as the light creates a shadow projected onto the table, this enhances the curved shape of the balls. This shows form as it allows you to see the balls are 3D.

I like how this image shows form as it's in black and white you can see the shadows easier, allowing your eyes to focus on the form aspect more. 

This image shows form as the shadows of the bark show how it's 3D, not a 2D image. 

This image shows form as on the back of the ladybirds backs you can see how they're 3D, the light hits the backs (the highlight area) and creates shadows below.

My own definition of form- how something may appear 3D, including shadows.