Looking for linguistic term

"Everyone is asked to bring their pencils for the exam."

This sentence sounds wrong to many, including myself, because 'everyone' is singular and 'their' is plural. The construction is widely used, however, because we don't have a word to use in place of 'their', short of 'his/her'; I don't want to start a discussion about that here. I am looking, rather, for the term used by linguists to take an existing word and apply it to a situation where something is needed.....other than creating another word itself. I remember an article which offered this term, and my memory has failed me since then, not being able to come up with it.

Example: "access", in 1969 was listed in the American Heritage Dictionary of English only as a noun. Today, because of the need for a verb shorter than to 'gain access to' in the technological arena, an example of this phenomenon has occurred, and now "access" is recognized as a verb in the same dictionary.

Not looking for suggestions as to what to call it, because I know there is already a term - just what is the term?

Thanks, y'all.