14-Letter Words Starting with O
There are 63 fourteen-letter words that start with O on Word.ws, from obsequiousness to oxidoreductase. The most common are organizational, overwhelmingly, osteoarthritis, overpopulation and overprotective.
Meanings from Wiktionary. Not an official Scrabble, Words With Friends or Wordle word list.
All 63 fourteen-letter words that start with O
OB
- obsequiousness25n. The quality of being obsequious; servile compliance.
- obstructionism20n. A deliberate policy of obstructing something, especially a political...
- obstructionist18n. Someone who systematically obstructs the actions of others.
OC
- occupationally23adv. As part of an occupation.
- oculocutaneous18adj. That affects the eyes and the skin.
OM
- omnibenevolent21adj. All-loving, or infinitely good, usually in reference to a deity or...
ON
- onchocerciasis23n. A disease caused by a worm of the genus Onchocerca, especially as...
OP
- operationalize25v. To make operational.
- ophthalmologic27adj. Ophthalmological.
- ophthalmopathy32n. Eye disease.
- ophthalmoscope28n. An instrument for examining the interior of the eye (that is, for...
- ophthalmoscopy31n. Examination of the eye with an ophthalmoscope.
- oppressiveness21n. The characteristic of being oppressive.
- optimistically23adv. In an optimistic manner.
- optoelectronic20adj. Of or pertaining to optoelectronics.
- optomechanical25adj. Of or pertaining to optomechanics.
OR
- organizational24adj. Of, relating to, or produced by an organization.
- organochlorine20n. Any of very many chlorine substituted organic compounds, many of which...
- organometallic19adj. Of, or relating to organic compounds having a metal atom directly...
- ornithological20adj. Of or pertaining to ornithology.
- orthochromatic26adj. Being uniformly sensitive across the entire visible range, and thus...
- orthographical25adj. Of, or relating to orthography or spelling.
- orthomolecular21adj. Relating to the theory that human health, including mental illness...
- orthophosphate27n. Any salt or ester of orthophosphoric acid; an ordinary phosphate.
OS
- osmoregulation17n. The homeostatic regulation of osmotic pressure in the body in order to...
- ostentatiously17adv. In an ostentatious manner; extravagantly or flamboyantly.
- osteoarthritic19adj. Affected with osteoarthritis.
- osteoarthritis17n. A form of arthritis, affecting mainly older people, caused by chronic...
- osteodystrophy26n. Any abnormal or defective development of a bone.
- osteosynthesis20n. The reduction and fixation of a bone fracture with implantable devices...
OT
- otolaryngology22n. The study of diseases of the ear, nose and throat.
OU
- outlandishness18n. The quality of being outlandish.
- outperformance23n. The act or state of outperforming.
- outrageousness15n. The quality of being outrageous.
OV
- overaggressive22adj. Overly aggressive; of a personality, action or behavior having...
- overcommitment25n. The act or situation of overcommitting.
- overcompensate23v. To do an excessive amount in one area in an effort to overcome a...
- overcomplicate25v. To make something excessively complicated.
- overconfidence25n. An excessive or unwarranted degree of confidence.
- overcorrection21n. The correction of something to an excessive degree, usually resulting...
- overdependence23n. Excessive reliance or dependence on something.
- overdetermined21adj. Having more constraints or causes than necessary to determine a...
- overestimation19n. The act of overestimating.
- overexcitement28n. The condition of being excessively excited.
- overexpression26n. The abnormal or artificial expression of a gene in increased quantity.
- overharvesting24n. Excessive harvesting.
- overindulgence21n. An act of overindulging; indulgence in too much; pleasure or...
- overinvestment22n. Excessive investment, especially in one particular area.
- overoptimistic23adj. Excessively optimistic.
- overperforming25adj. That performs better than required.
- overpopulation21n. An excessive number of occupants (people, animals, plants, etc.) in a...
- overpoweringly26adv. In an overpowering manner.
- overprivileged24adj. Being too privileged; specifically, having more advantages or...
- overproduction22n. The production of more of a commodity than can be used or sold.
- overprotection21n. The act of overprotecting.
- overprotective24adj. Excessively protective, wanting to give too much protection (especially...
- overregulation18n. Excessive regulation: too many rules, especially misguidedly conceived...
- oversaturation17n. Supersaturation.
- oversimplified25adj. Having been simplified to the point where important information is not...
- overstimulated20adj. Excessively stimulated.
- oversubscribed24adj. Having insufficient capacity to meet the demand of those who are...
- overwhelmingly29adv. In an overwhelming manner; very greatly or intensely.
OX
- oxidoreductase25n. Any enzyme that catalyzes an oxidation-reduction (redox) reaction.
745 rare fourteen-letter words that start with O
- obdiplostemony
- obeliscolychny
- objectlessness
- oblanceolately
- obligativeness
- obligatoriness
- obliquolateral
- obliteratingly
- obliteratively
- oblongichytrid
- oblongitudinal
- obreptitiously
- obscurantistic
- obscurationism
- observableness
- obsessionalism
- obsessionality
- obstetrication
- obstreperosity
- obstreperously
- obstructedness
- obstupefaction
- occasionalness
- occipitoatloid
- occipitofacial
- occipitomental
- occipitonuchal
- occipitosacral
- occupationaire
- occupationless
- occurrentially
- oceanographist
- ocelloccipital
- ochratoxicosis
- ochratoxigenic
- octadecacopper
- octadecahedral
- octadecahedron
- octadecanamide
- octadecylamine
- octamerization
- octanucleotide
- octaphosphorus
- octasaccharide
- octocentennial
- octocontrabass
- octonionically
- octopaminergic
- octreoscanning
- octylglucoside
- ocularcentrism
- oculoauricular
- oculoglandular
- oculomotricity
- oculopalpebral
- oculopupillary
- oculozygomatic
- odonatological
- odontodactylid
- odontognathous
- odontoidectomy
- odontonecrosis
- odontopathogen
- odontoskeletal
- odorranalectin
- oenotheraceous
- oestrogenicity
- offshorization
- oldfangledness
- oldsightedness
- oleaginousness
- oleodistillate
- oleophobically
- olericulturist
- oligarchically
- oligoadenosine
- oligoadenylase
- oligoadenylate
- oligoanalgesia
- oligoantigenic
- oligoarthritic
- oligoarthritis
- oligoarticular
- oligobenzamide
- oligocellulose
- oligochaetotic
- oligochromatic
- oligoclonality
- oligocythaemic
- oligodendrimer
- oligodendritic
- oligofectamine
- oligogenically
- oligoglucoside
- oligoglutamate
- oligoglutamine
- oligoglycoside
- oligoguanidine
- oligohexameric
- oligohistidine
- oligohydramnic
- oligoisolating
- oligomannoside
- oligomenorrhea
- oligoovulation
- oligopeptidase
- oligophenylene
- oligophosphate
- oligopithecine
- oligopotential
- oligoprecursor
- oligopsonistic
- oligorecurrent
- oligosaccharyl
- oligosarcosine
- oligosecretory
- oligospermatic
- oligostemonous
- oligosynthesis
- oligosynthetic
- oligothiophene
- oligothymidine
- oligoubiquitin
- oligouridylate
- omalodontiform
- omniaperturate
- omnibenthivore
- omnicognizance
- omnicompetence
- omnilaterality
- omnilinguality
- omnimalevolent
- omnipercipient
- omniphobically
- omnipotentiary
- omnipresential
- omniprevalence
- omnispatiality
- omnisufficient
- omnitemporally
- omnitruncation
- omnivoropteryx
- omnivorousness
- omphalocentric
- omphalopsychic
- omphaloskepsis
- omphaloskeptic
- omphalotrochid
- oncogeneticist
- oncogeriatrics
- oncohematology
- oncoimmunology
- oncometabolite
- oncomiracidial
- oncomiracidium
- oncomodulation
- oncomodulatory
- oncoprotective
- oncoproteomics
- oncoretroviral
- oncoretrovirus
- oncosuppressor
- oneirocritical
- oneirocritique
- onomasiologist
- onomatological
- onomatopoeious
- onomatopoiesis
- onomatopoietic
- ontogeneticist
- ontologization
- ontotheologian
- ontotheologist
- onychogryposis
- oophorectomize
- oosporogenesis
- oosterboschite
- operationalism
- operationalist
- operationality
- operationistic
- operculiferous
- operculigenous
- operculigerous
- ophidiomycosis
- ophiocephalous
- ophiopojaponin
- ophiostomatoid
- ophthalmectomy
- ophthalmically
- ophthalmodynia
- ophthalmometer
- ophthalmometry
- ophthalmospasm
- ophthalmotrope
- opilionologist
- opiniativeness
- opinionatively
- opisthocoelian
- opisthocoelous
- opisthocranion
- opisthodelphic
- opisthodontian
- opisthogastric
- opisthognathid
- opisthographic
- opisthoproctid
- opisthorchidal
- opisthoteuthid
- opotherapeutic
- oppenheimerite
- opportunitroph
- oppositionally
- oppositionless
- oppositiveness
- opsonification
- opticochemical
- optimizational
- optionlessness
- optochiasmatic
- optoepigenetic
- optometrically
- optophysiology
- optospintronic
- orbiculatoside
- orbitocerebral
- orbitohyoideus
- orbitosphenoid
- orbitostenosis
- orbitostriatal
- orbitotemporal
- orchidectomist
- orchidectomize
- orchidological
- orchiectomised
- orchiectomized
- ordoliberalism
- ordoliberalist
- organellometry
- organification
- organismically
- organizability
- organoactinide
- organoammonium
- organoantimony
- organoboronate
- organocatalyst
- organochemical
- organochloride
- organochromium
- organodetrital
- organoeuropium
- organofluoride
- organofluorine
- organogelation
- organographist
- organohydrogen
- organolutetium
- organomercuric
- organomodified
- organonitrogen
- organoperoxide
- organoplatinum
- organopolonium
- organorubidium
- organosamarium
- organoscandium
- organoselenide
- organoselenium
- organosiloxane
- organospecific
- organostannane
- organotantalum
- organothallium
- organotitanate
- organotitanium
- organotolerant
- organotungsten
- organotypicity
- organovanadium
- orientationist
- orientifolding
- originlessness
- ornamentalness
- ornithocheirid
- ornithochorous
- ornithomorphic
- ornithophagous
- ornithophilist
- ornithophilous
- ornithoscopist
- ornithuromorph
- orobanchaceous
- orodispersible
- orogastrically
- orographically
- orohypopharynx
- oronasopharynx
- orthoaluminate
- orthoamphibole
The first 300 are shown.
Questions about these words
- How many fourteen-letter words that start with O are there?
- Word.ws lists 63 fourteen-letter words that start with O, plus 745 rare ones.
- What are common fourteen-letter words that start with O?
- organizational, overwhelmingly, osteoarthritis, overpopulation, overprotective, optimistically, overexpression and overproduction.
- Which of the fourteen-letter words that start with O has the highest letter score?
- ophthalmopathy scores 32 points with the standard letter tile values.
Related word lists
Source and license
Word lists and meanings adapted from the Wiktionary entry of each word. Text available under the Creative Commons Attribution-ShareAlike 4.0 license. Word.ws left out names, abbreviations, misspellings and offensive words, and ordered the most common words by how often they appear in English (wordfreq). Meanings from Wiktionary; this is not an official Scrabble, Words With Friends or Wordle word list. Wiktionary data of 2026-09-02.
Cite this page: “14-Letter Words Starting with O: 63 Words.” Word.ws, https://word.ws/words/14-letter/starting-with-o. Based on Wiktionary, CC BY-SA 4.0.