One of the students asked whether the "Chadwick neutron" was the same "neutron" proposed by Pauli for the phenomena of beta transformation. "No," answered Fermi, "il neutrone di Pauli e mol to piupiccolo, cio e un neutrino." The name stuck.
The Reality of Neutrinos, Physics Today, Volume 1, Number 3, July 1948 (p. 5)