How do you define something?

When you have something, that is made from basics, you can define him, by telling these basics, and how they react together to construct that something.

* Bread - made of flour and water mixed together, baked.

But, if something is in itself a basic (something that cannot be split, even if it's a rather complicated thing) - it cannot be defined.

Therefore, some questions have no answers (or no legitimation to be asked).

Examples: What is a soul, what is light, what is water, soil.

===

Defining stuff is limited to our 5 senses.

How can I define an apple?

By its taste, smell, touch, look (and sound).

So how do you define infra-red? or ultra-violet? or electric flow? wind, you can feel on your skin.

(okay electric flow is tiny things that behave like waves. but infra-red is just an actual wave - how did people even find it? how do we know that bees can see it? trial and error?)

You see, there's this thing called science...

edit: there is much more to bread than flour and water.