Here's why:

* Structure: Diethyl ether has a symmetrical structure (CH3CH2-O-CH2CH3). The oxygen atom is bonded to two identical ethyl groups, and the molecule has a symmetrical arrangement of its atoms.

* Electronegativity: Oxygen is more electronegative than carbon and hydrogen, so it pulls electron density towards itself. However, the symmetrical structure of diethyl ether ensures that these polar bonds cancel each other out.

* Dipole Moment: Due to the cancellation of polar bonds, diethyl ether has a very small or negligible dipole moment. This indicates a nonpolar molecule.

Therefore, diethyl ether is considered a nonpolar solvent.