12 letter nouns that start with O
We have listed 110 12-letter nouns that start with O for you in this WordMom word list. All these 12-letter nouns starting with O were verified by specialists in the English language.
- oathbreaking
- obsolescence
- obstetrician
- obliteration
- obscurantism
- obscurantist
- obsoleteness
- obligingness
- obmutescence
- obtruncation
- obtrusionist
- observantine
- observership
- obedienciary
- obtrectation
- oceanography
- octogenarian
- octosyllable
- odontography
- odontopteryx
- oesophagitis
- oenanthylate
- officeholder
- oligospermia
- oligodactyly
- oligodendria
- omnipresence
- omphalomancy
- omnipresency
- onomatopoeia
- oneiromancer
- onychophoran
- onomatomania
- oophorectomy
- oosporangium
- optimization
- opisthotonos
- oppositeness
- optimisation
- opsonization
- ophthalmitis
- opsonisation
- opposability
- opinionatist
- organization
- orthopaedics
- orthopaedist
- organisation
- orthodontics
- orthodontist
- ordinariness
- orchestrator
- orchidectomy
- ornithoscopy
- orthographer
- organography
- ornithomancy
- orthodromics
- ornithomimid
- orphenadrine
- orthodonture
- oryctologist
- orbiculation
- originalness
- ordinability
- orthodoxness
- ordinaryship
- oryctography
- ossification
- osteoporosis
- oscilloscope
- osteomalacia
- osteosarcoma
- osteopathist
- oscillograph
- osteogenesis
- osteostracan
- osmoreceptor
- osteocranium
- osteodentine
- osteographer
- otosclerosis
- otacousticon
- ouranography
- overestimate
- overexertion
- overachiever
- overemphasis
- overreaction
- overexposure
- overpressure
- overlordship
- overactivity
- overpraising
- overmuchness
- overfullness
- overcrossing
- ovariotomist
- overmeddling
- overseership
- overmoisture
- overshadower
- oxyacetylene
- oxaloacetate
- oxymethylene
- oxyquinoline
- oxalethyline
- oxamethylane
- oxanillamide
- oxysulphuret