IPA: /ɪˈnɒkjʊleɪtə/
KK: /ɪˈnɑkjʊˌleɪtər/
A person who introduces a substance into a living organism to create immunity or to propagate plants or diseases.
The inoculator carefully administered the vaccine to ensure the patients developed immunity.
Inoculator → It is formed from "in-" (meaning into) and "oculare" (meaning to place in or to introduce). The word refers to someone who introduces a substance, typically a vaccine, into the body.
Think of someone 'placing' ('oculare') something 'into' ('in-') the body — that's why inoculator means a person who introduces a vaccine.