Exactly which objects should we considered as colorless?

Question

My question is which objects are considered as colorless? In chemistry we sometimes consider white object as colorless,Many times we use the word colorless for transparent substances like water, glass, etc. But what exactly is colorless in physics?

I thought about this and I think colorless should be referred to the black body,Since black body doesn't reflect any light therefore it must be colorless.

I don't know if I am right or wrong.

Does this answer your question? How the term 'colorless' is defined in physics? — joseph h, Jan 13 '24 at 06:53
Part of this is just vocabulary. You might say the color of an object is white and white is a color. But a white object is also colorless by John Rennie's definition. It reflects all light that hits it, and does not change its color. — mmesser314, Jan 13 '24 at 16:47
Closing this as a duplicate of the linked question is backward. The answer here is better. — mmesser314, Jan 13 '24 at 16:50

score 2 · Accepted Answer · answered Jan 13 '24 at 05:44

A colourless object does not change the spectrum of the light that it transmits or reflects. So if you shine red light at a colourless object it will transmit or reflect red light, and if you shone blue light at it the colourless object will transmit or reflect blue light.

This does not apply to a black body since the spectrum of the light emitted depends only on the temperature of the black body and not on the light that you shone at it.

Exactly which objects should we considered as colorless?

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