CONTROLLED is all it means..

The terms inoculation, vaccination, and immunization are often used synonymously, but there are some important differences among them.

What does inoculate mean?
1 a : to introduce a microorganism into. b : to introduce

(something, such as a microorganism) into a suitable situation for growth. c : to introduce immunologically active material (such as an antibody or antigen) into especially in order to treat or prevent a disease. 2 : to introduce something

into the mind of.
What is the meaning of vaccines?
preparation of killed microorganisms
: a preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to

produce or artificially increase immunity to a particular disease

Immunization, is the process by which an individual's immune system becomes fortified against an agent (known as the immunogen).

When this system is exposed to molecules

that are foreign to the body, called non-self, it will orchestrate an immune response, and it will also develop the ability to quickly respond to a subsequent encounter because of immunological memory. This is a function of the adaptive immune system.

Therefore, by exposing an animal to an immunogen in a CONTROLLED way, its body can learn to protect itself: this is called active immunization.