  We investigate various types of squeezing in a collective su(2J+1) system
consisting of spin-J particles (J>1/2). We show that the squeezing in the
collective su(2J+1) system can be classified into unitary equivalence classes,
each of which is characterized by a set of squeezed and anti-squeezed
observables forming an su(2) subalgebra in the su(2J+1) algebra. The
dimensionality of the unitary equivalence class is fundamentally related to its
squeezing limit. We also demonstrate the classification of the squeezing among
the spin and multipolar observables in a collective su(4) system.
