Why does the "git index" have so many names?

While reading how to use Git, I found a lot of different names for git index.

They were:

• directory cache
• current directory cache
• staging files
• staging area

How come there are so many options to name exactly one thing?

How I should to name it to not to confuse my future interlocutors whose backgrounds I do not know?

From my experience, the most commonly used term is Staging Area.

Evidence:

• Files and folders are referred to as Staged and Unstaged in the Git system when performing git commands.
• From what I've observed: Most developers only read the Getting Started - Git Basics documentation when first starting out with Git. This document refers to it as the Staging Area.
• As someone who works a lot with Git and often surrounded by people who work a lot with it to, most developers I've met refer to it as the Staging Area.