is called the adiabatic bulk modulus, and its inverse is call
the adiabatic compressibility. It is common but sloppy to call
them "the" bulk modulus and "the" compressibility.
For ideal gases, it is equal to the adiabatic index i.e. the
ratio of specific heats i.e. γ .... We don't need a new
name for that; there are more than enough names already.
On the other hand, for water at 1 atm, the ratio of specific
heats is close to unity, whereas the dimensionless modulus
in eq. [2] is 22000 times greater than that.
If it helps, note that I am actually more interested in the
compressibility-like quantity
- ∂ ln V |
?? = -------- | [3]
∂ ln P |S
Is there a conventional name for either of [2] or [3], and/or
can anybody suggest a nice name?