Whatever engine powered it was mysterious to me; it seemed to throb, a distinctly unstable mass.

The wild weather was created when cold air moving rapidly down from Canada collided with a warm, moist, unstable mass of air, he said.

Hemp gave a wasp thrum in warning; the unstable mass teetered, then cracked and heeled over to bash into the next row of racks.

The cloud appears to be composed of long strips of reflective river surface that have been loosely wrapped, an unstable mass of creative energy.

Behind him one of the Irakzai reached out and thrust his sword into the unstable mass.

Her feet scrabbled to get a foothold in the unstable mass; it took several efforts before she had raised herself sufficiently to get her forelegs over the lip of the tunnel.

How could adding some neutrons (and such a small percentage) to an unstable mass make it more stable.

Turbidity currents are dense, sediment-laden currents which flow downslope when an unstable mass of sediment that has been rapidly deposited on the upper slope fails, perhaps triggered by earthquakes.

Conan blinked and shook the blood from his own eyes; it seemed to him that the thing was melting and disintegrating into a slimy unstable mass.

Behind it I heard a repulsive obscene noise as of a quaking unstable mass heaving up out of a well.