  We report three-dimensional trapping of an oxide molecule (YO), using a
radio-frequency magneto-optical trap (MOT). The total number of molecules
loaded is $\sim$1.5$\times10^4$ , with a temperature of 7(1)~mK. This
diversifies the frontier of molecules that are laser coolable and paves the way
for the second-stage narrow-line cooling in this molecule to the microkelvin
regime. Futhermore, the new challenges of creating a 3-D MOT of YO resolved
here indicate that MOTs of more complex non-linear molecules should be feasible
as well.
