  Addressing the mass origin and properties of neutrinos is of strong interest
to particle physics, baryogenesis and cosmology. Popular explanations involve
physics beyond the standard model, for example, the dimension-5 Weinberg
operator or heavy Majorana neutrinos arising from ``seesaw'' models. The
current best direct limits on the electron neutrino mass, derived from nuclei
beta decay or neutrinoless double beta decay processes, are at the
sub-electronvolt level. Here we propose a novel neutrino neutrino collider
where the neutrino beam is generated from TeV scale muon decays. Such
collisions can happen between either neutrinos and anti-neutrinos, or neutrinos
and neutrinos. We find that with a tiny integrated luminosity of about
$10^{-5}$/fb we can already expect to observe direct neutrino anti-neutrino
annihilation, $\nu\bar{\nu}\rightarrow {\rm Z}$, which also opens the door to
explore neutrino related resonances $\nu\bar{\nu}\rightarrow {\rm X}$. The low
luminosity requirement can accommodate a relatively large emittance muon beam.
Such a device would also allow for probing heavy Majorana neutrino and
effective Majorana neutrino mass through $\nu\nu\rightarrow {\rm H H}$ to a
competitive level, for both electron and muon types.
