Co2
Mercury, aka: "Quick Silver"
no salt is not compressible
Butane gas is compressible. It can be compressed into a smaller volume at higher pressures.
Compressible, Low Viscosity (compared to a liquid)
All gases are compressible (even all fluids and solids are, though much lesser), so there is no special name needed for this group because it is not special.
The correct name for the graduation hat is a mortarboard.
Sodium chloride is compressible.
One of the synonyms for "compressible" is "squeezable". I've noticed that a sponge is more compressible when it is soaking wet.
The name of a traditional magician's hat is a top hat. This is the hat that magician's use to pull rabbits, birds and scarves out of.
Fluids include liquids and gasses. Liquids are not compressible. Gasses are compressible. Water is a liquid and it not compressible.
Sponge is solid yet it is compressible the presence of the inter particle spaces or voids which are filled with air and make it compressible.