15-Letter Words Start with 'o'

There are 157 15-letter words that start with 'o'.

objectification	objectivenesses
obliviousnesses	obnoxiousnesses
observabilities	observationally
obsessivenesses	obstinatenesses
obstructionisms	obstructionists
obstructiveness	obtainabilities
obtrusivenesses	occidentalizing
oceanographical	odoriferousness
offensivenesses	offhandednesses
officiousnesses	oxidoreductases
oxyphenbutazone	oxytetracycline
oligodendrocyte	oligodendroglia
oligomerization	oligonucleotide
oligosaccharide	omnicompetences
omnidirectional	ontogenetically
openheartedness	openmouthedness
operationalisms	operationalists
operativenesses	ophthalmologies
ophthalmologist	ophthalmoscopes
ophthalmoscopic	opinionatedness
opportunenesses	opprobriousness
optoelectronics	orchestrational
organochlorines	organomercurial
organometallics	organophosphate
orientationally	orthodontically
orthogonalities	orthogonalizing
orthophosphates	orthopsychiatry
oscillographies	osmoregulations
osteomyelitises	osteopathically
outdoorsmanship	outmanipulating
outspokennesses	overaccentuated
overaccentuates	overachievement
overadjustments	overadvertising
overapplication	overarticulated
overarticulates	overassessments
overcapitalized	overcapitalizes
overcentralized	overcentralizes
overclassifying	overcommitments
overcommunicate	overcompensated
overcompensates	overcompliances
overcomplicated	overcomplicates
overcompressing	overconfidences
overconfidently	overconstructed
overconsumption	overcontrolling
overcultivation	overdecorations
overdependences	overdevelopment
overdiscounting	overdiversities
overdocumenting	overdramatizing
overeagernesses	overelaborating
overelaboration	overembellished
overembellishes	overemphasizing
overencouraging	overengineering
overentertained	overenthusiasms
overestimations	overevaluations
overexaggerated	overexaggerates
overexpectation	overextractions
overextravagant	overfamiliarity
overfertilizing	overgeneralized
overgeneralizes	overglamorizing
overhomogenized	overhomogenizes
overidentifying	overimaginative
overindulgences	overingenuities
overintensities	overinvestments
overlengthening	overmedications
overopinionated	overorchestrate
overornamenting	overpersuasions
overpopulations	overprescribing
overproductions	overprogramming
overproportions	overprotections
overrefinements	overregulations
overrepresented	oversaturations
oversensitivity	oversimplifying
overspecialized	overspecializes
overspeculating	overspeculation
overstabilities	overstimulating
overstimulation	oversubscribing
oversweetnesses	overutilization
overwithholding	overzealousness
ovoviviparously

Note: These 157 15-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)