To shut up or place in an enclosure called a pound
His car got impounded after he'd parked illegally.
To hold back (for example water by a dam)
To hold in the custody of a court or its delegate
to impound stray cattle; to impound a document for safe keeping.
To collect and hold (funds) for payment of property taxes and insurance on property in which one has a security interest
An act of impoundment.