Here's why:

* Structure: Diethylamine (CH3CH2)2NH has a nitrogen atom with a lone pair of electrons, which creates a dipole moment.

* Polarity: The presence of this dipole moment makes the molecule polar.

* Solubility: Polar solvents dissolve polar compounds, and nonpolar solvents dissolve nonpolar compounds. Diethylamine is miscible with water, which is a polar solvent, indicating its own polar nature.

Therefore, diethylamine is a polar solvent, not a nonpolar solvent.