The term "coloured hydroxide" is a bit vague. It's important to understand that hydroxides are compounds containing the hydroxide ion (OH-), which is a colorless ion. However, the metal cation in a metal hydroxide can often give the compound its color.

Here are some examples:

* Copper(II) hydroxide (Cu(OH)₂) is blue. The blue color comes from the copper(II) ion (Cu²⁺).

* Iron(II) hydroxide (Fe(OH)₂) is green. The green color comes from the iron(II) ion (Fe²⁺).

* Iron(III) hydroxide (Fe(OH)₃) is reddish-brown. The reddish-brown color comes from the iron(III) ion (Fe³⁺).

Therefore, a "colored hydroxide" is a hydroxide compound that exhibits a visible color due to the presence of a colored metal cation.

It's important to note:

* Not all hydroxides are colored. Many alkali and alkaline earth metal hydroxides are colorless or white.

* The color of a hydroxide can be influenced by factors like pH, concentration, and impurities.

To give you a more specific answer, I need more context. Can you please specify what "colored hydroxide" you are referring to? For example, are you asking about a specific chemical compound, a solution, or a reaction?