12-Letter Words Start with 'o'

There are 439 12-letter words that start with 'o'.

oafishnesses	oarsmanships	obdurateness
obfuscations	objectifying	objectivisms
objectivists	objurgations	oblanceolate
oblatenesses	obligatorily	obligingness
obliterating	obliteration	obliterative
obliterators	obnubilating	obnubilation
obscurantism	obscurantist	obscurations
obsequiously	observations	obsolescence
obsoleteness	obstetrician	obstreperous
obstructions	obstructives	obtusenesses
occasionally	occidentally	occultations
occupational	oceanography	oceanologies
oceanologist	ochlocracies	octahedrally
octapeptides	octogenarian	octosyllabic
octosyllable	odiousnesses	odontoblasts
officeholder	officialdoms	officialeses
officialisms	officiations	offishnesses
oxyacetylene	oxygenations	ozonizations
ozonospheres	offscourings	oleaginously
oleandomycin	oleoresinous	olfactometer
oligarchical	oligochaetes	oligophagies
oligophagous	oligopsonies	oligotrophic
omnipotences	omnipotently	omnipresence
omnisciences	omnisciently	omnivorously
oncogenicity	oncornavirus	onomastician
onomatopoeia	onomatopoeic	onychophoran
oophorectomy	opalescences	opalescently
opaquenesses	openhandedly	operatically
operationism	operationist	operatorless
opinionative	opportunisms	opportunists
opposability	oppositeness	oppositional
oppressively	optimalities	optimisation
optimization	optometrists	oratorically
orchestrally	orchestrated	orchestrater
orchestrates	orchestrator	orchidaceous
ordinariness	organicities	organisation
organization	organoleptic	organologies
orientalisms	orientalists	orientalized
orientalizes	orientations	orienteering
originations	orismologies	ornamentally
ornatenesses	ornerinesses	ornithologic
ornithopters	orographical	oropharynges
oropharynxes	orotundities	orthocenters
orthodontias	orthodontics	orthodontist
orthogeneses	orthogenesis	orthogenetic
orthogonally	orthographic	orthopaedics
orthopedists	orthopterans	orthopterist
orthopteroid	orthorhombic	orthotropous
oscillations	oscillograms	oscillograph
oscilloscope	osmolalities	osmolarities
ossification	ostentations	ostentatious
osteoblastic	osteoclastic	osteogeneses
osteogenesis	osteological	osteologists
osteomalacia	osteopathies	osteoplastic
osteoporoses	osteoporosis	osteoporotic
osteosarcoma	ostracoderms	otherworldly
otiosenesses	otoscleroses	otosclerosis
outachieving	outbalancing	outbargained
outbrazening	outbreedings	outbuildings
outcavilling	outcompeting	outcroppings
outdatedness	outdelivered	outdesigning
outdistanced	outdistances	outgalloping
outgeneraled	outglittered	outgoingness
outintrigued	outintrigues	outjockeying
outlandishly	outmaneuvers	outmastering
outnumbering	outorganized	outorganizes
outperformed	outplacement
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Note: These 439 12-letter words that start with 'o' are found from the USA & Canada version of the tournament Scrabble word list.

Also see words start with ov, ou, or, ob, op, os, oc, ox, ol, on, of, om, od, oo, ot, oi, oa, oe, og, oz, ow, oy, ok, oh, oq.

2-letter words start with 'o' (13)
3-letter words start with 'o' (48)
4-letter words start with 'o' (112)
5-letter words start with 'o' (185)
6-letter words start with 'o' (341)
7-letter words start with 'o' (645)
8-letter words start with 'o' (1,012)
9-letter words start with 'o' (1,065)
10-letter words start with 'o' (880)
11-letter words start with 'o' (646)
12-letter words start with 'o' (439)
13-letter words start with 'o' (301)
14-letter words start with 'o' (213)
15-letter words start with 'o' (157)