Nouns ending with the letter X are listed here.
apex
borax, box
climax, complex, cortex, crucifix, crux
fix, flax, flex, flux, fox
hex
icebox, index, influx
jinx
latex, lummox
mailbox, matrix, mix
neocortex, nux
paradox, phalanx, premix
reflex
sax, smallpox, suffix, syntax
tax
vertex, vortex
wax
What about ox?