Physics can be defined as the science of matter, motion, and energy.

Agriculture is defined as the cultivation of soil for growing crops.

Genius has been defined as a supreme capacity for taking trouble.

Some words are hard to define.

It is hard, perhaps even impossible, to define normal sensory perception.

In mathematics, a straight line is defined by two points.

A dictionary defines words.

I will define happiness as this.

To give a definition of a word is more difficult than to give an illustration of its usage.

The word 'excessive competition' is frequently used in Japanese industry, but there is not a precise definition of the practice.

Can you give me the definition of a cone?

If I had to define life in a word, it would be: Life is creation.

Boxing has been defined as the art of hitting without being hit.

Above all, logic requires precise definitions.

Above all, scientific terms call for precise definitions.

Instead, I will turn to a discussion of the two economic variables I defined a moment ago.

Can you clearly define this word?

How would you define "happiness"?

It is hard to define "triangle."