immunise: to deliberately administer an antigen to an individual in such a way that the individual develops an adaptive immune response to the antigen

immune: the state of being able to mount an adaptive immune response against an antigen that the individual has been exposed to before. An individual can become immune through immunisation or as a result of natural infection. Immunity can wane over time, so an individual may no longer be immune if they have been immunised in the past

inoculate: means the same as vaccinate and has been largely replaced by vaccinate when referring to human immunisation; still used in cell culture (for introducing cells into a new culture medium) and in animal research (for introducing a microorganism into a laboratory animal)

vaccinate: to administer antigenic material (a vaccine) to stimulate an individual’s immune response. The aim of vaccination is for the individual to be immunised (ie to become immune); however, an individual can be vaccinated but not become immune (eg as a result of vaccine failure)