sourpusssour‧puss /ˈsaʊəpʊs $ ˈsaʊr-/ noun [countable] old-fashioned 
someone who complains a lot and is never happy or satisfied
someone who complains a lot and is never happy or satisfied- operationally
- operational research
- Operation Desert Storm
- Operation Iraqi Freedom
- Operation Overlord
- operative
- operator
- operetta
- Ophelia
- ophthalmic
- ophthalmologist
- ophthalmology
- opiate
- opine
- opinion
- opinionated
- opinion-makers
- opinion poll
- opium
- opossum
- opp.
- Oppenheimer, J. Robert
- opponent
- opportune
- opportunely