DORSUM   :   

A ridge.

DRIVING FORCE   :   

A terminology used in thermodynamics expressing the availability of energy to 'drive' a process such as mechanical work or chemical synthesis. Driving forces exist where a potential gradient exist. A potential gradient can be in form of a temperature gradient causing heat to flow, an electrical gradient causing electrons or ions to flow, or a concentration gradient causing diffusion.

DUST (COSMIC)   :   

Tiny particles that are just a few angstroms in size produced by the supernovae explosions and asteroid collisions are known as the cosmic or instersellar dust.

DYNAMO   :   

This is a device that is used to create electricity by turning around a magnet near a wire coil.