The terminology used to describe the prevention of smallpox can cause confusion. In 18th-century medical terminology, inoculation refers to smallpox inoculation. Confusion is caused by writers who interchange<unk>  and vaccination through either mistranslation or misinterpretation. The term<unk>  refers solely to inoculation with smallpox virus and is related to but not interchangeable with vaccination. The latter term was first used in 1800 soon after Edward Jenner introduced smallpox vaccine derived from cowpox, an animal disease distinct from smallpox. The term<unk>  was then used from the 19th century to avoid confusion with vaccination. Most modern writers tend to refer to smallpox inoculation as<unk>  throughout without regard for chronology, as is used here. Further confusion was caused when, in 1891, Louis Pasteur honoured Jenner by widening the terms vaccine/vaccination to refer to the artificial induction of immunity against any infectious disease. Inoculation refers to intentionally exposing an individual to a virus, bacterium, other pathogen, or artificial vaccine that may induce active immunity, and inoculation can be done by any suitable route of administration. Many familiar vaccines are injected intramuscularly or swallowed. The term "inoculation" entered medical English through horticultural usage meaning to graft a bud (or eye) from one plant into another. It is derived from the Latin in + oculus (eye)..
Variolation
Dominance 
Penetrance
Cordance
Involution 
Deformity
Concept creep
Latent inhibition