You're almost there! Leucocytes are indeed colorless, but they are not the only colorless part of your body.

Here's a breakdown:

* Leucocytes (White Blood Cells): These are the colorless cells of your blood that fight infections. They are colorless because they lack hemoglobin, the red pigment that gives red blood cells their color.

* Plasma: This is the fluid component of your blood, which is also colorless. It carries the blood cells, nutrients, hormones, and waste products throughout your body.

* Other Body Fluids: Many other bodily fluids, like lymph, cerebrospinal fluid, and saliva, are also colorless.

So, while leucocytes are colorless, they are just one of many colorless components in your body.