12-Letter Words Starting with O

Obfuscation

Objectivism

Objectivist

Obscuration

Hindrances

Noisy disturbances on street after outside broadcast means barriers

Obstructive

Occultation

Oceanology

Ochlocracy

Octapeptide

Officialdom

Officialese

Officialism

Officiation

Offscouring

Oligochaete

Omnipotence

Omniscience

Any of a group of viruses that contain single-stranded RNA and produce tumors in birds and mammals.

Opalescence

Arranges music

Narrow passages for killer whales (wordplay)

""Pertaining to, or resembling, a natural order (Orchidace\'91) of endogenous plants of which the genus Orchis is the type. They are mostly perennial herbs having the stamens and pistils united in a single column, and normally three petals and three sepals, all adherent to the ovary. The flowers are curiously shaped, often resembling insects, the odd or lower petal (called the lip) being unlike the others, and sometimes of a strange and unexpected appearance. About one hundred species occur in the United States, but several thousand in the tropics. Orchidace\'91) of endogenous plants of which the genus Orchis is the type. They are mostly perennial herbs having the stamens and pistils united in a single column, and normally three petals and three sepals, all adherent to the ovary. The flowers are curiously shaped, often resembling insects, the odd or lower petal (called the lip) being unlike the others, and sometimes of a strange and unexpected appearance. About one hundred species occur in the United States, but several thousand in the tropics.""

Organicity

Orthocenter

Canine training (wordplay)

Correction of dental irregularities

Branch of dentistry

The treatment of bone and muscle disorders

Rum do, as her topic is a medical speciality

Devious colonialists making waves

Oscillogram

Ostracoderm

Plural or third person singular

""A disease of the ear in which the movement of the stapes within the oval window becomes impeded by abnormal deposits of spongy bone, leading to a progressive loss of hearing.""

Outcropping

Leaves behind.

Outpolitick

Outsourcing

Outstretch

Overachieve

Overbalance

Overbleach

Overcasting

Overcaution

A curious vote, sadly going for the ultra-safe option (wordplay)

COMPRESS to {compact=v}

Overconcern

Overconsume

Overcontrol

Overcorrect

Overeducate

FOCUSSES focus

Overpackage

Overproduce

Overprotect

REACHERS reacher

Overservice

Oxalacetate