os 1 
(ōs)
(ōs)n. pl. o·ra (ôrə)
A mouth or an opening.
[Latin ōs, mouth; see ōs- in the Appendix of Indo-European roots.]
- third person
- third-person
- third quantum number
- third quarter moon
- third rail
- third-rate
- Third Reich
- third-stream
- third stream
- Third World
- Third-World
- Third Worlder
- thirst
- cryptobiosis
- cryptobiotic
- cryptoclastic
- cryptococcal
- cryptococcosis
- cryptococcus
- cryptocrystalline
- cryptogam
- cryptogamic
- cryptogamous
- cryptogenic
- cryptogenous