The pulse is said to be hard when the vessel feels hard and incompressible, the soft pulse being the opposite.
"Special Report on Diseases of Cattle"
U.S. Department of Agriculture J.R. Mohler
The bulge itself was an incompressible thing, like a roaring lift of the waters from submarine explosion.
"The Last of the Plainsmen"
Zane Grey
It cannot, however, do so to any significant extent by a contraction which would leave it similar to itself, because that would imply a squeezing in of the interior metal, which is still expanded by heat, and is almost incompressible.
"Modern Machine-Shop Practice, Volumes I and II"
Joshua Rose