Some singular nouns that end with on S are:
- abacus
- animus
- axis
- bias
- bonus
- bus
- cactus
- campus
- census
- chaos
- chorus
- circus
- debris
- dais
- esophagus
- fetus
- ficus
- genius
- hippopotamus
- hubris
- hummus
- ibis
- iris
- loris
- lotus
- mantis
- mucus
- nexus
- nucleus
- oasis
- octopus
- onus
- opus
- papyrus
- Paris
- pelvis
- penis
- radius
- rebus
- rhinoceros
- ruckus
- sinus
- status
- stimulus
- stylus
- surplus
- syllabus
- synopsis
- syphilis
- tennis
- thesaurus
- virus
- walrus