Opus Operatum

Opus Operatum (i.e. the work wrought), a Latin phrase used to denote the spiritual effect in the performance of a religious rite which accrues from the virtue inherent in it, or by grace imparted to it, irrespectively of the administrator.

Definition taken from The Nuttall Encyclopædia, edited by the Reverend James Wood (1907)

Optimism * Oran
Ophelia
Ophicleide
Ophir
Ophites
Opie, John
Opinicus
Opitz, Martin von
Oporto
Opportunist
Optimism
Opus Operatum
Oran
Orange River
Orange River Colony
Orangemen
Oratorio
Oratory, Congregation of the
Orcagna
Orchardson, William Quiller
Orcus
Ordeal