The uptake of water and solutes from the environment by a cell or a multi-celled organism; that is, the movement of nutrients, fluid, and ions across the gut lining and into the internal environment.

Dark narrow lines that represent absorption of energy at a particular wavelength of light: Absorption lines can be exemplified by each of the elements on the periodic chart which absorb energy at specific wavelengths of light, and that looks like a bar code.

A diffuse or dispersed cloud of interstellar dust or gas or both that is seen in silhouette as it absorbs light from behind: An absorption nebula is also called a "dark nebula".

The array of components resulting when light from one source is passed through another material: An absorption spectrum occurs in combination with a tenuous gas.

The result is a series of dark bands crossing the spectrum, known as absorption lines.