My suggestion is that when a Scratch-specific word shows up in the editor, on the site, or in a comment, a dropdown will show up if you hover over it giving the definition.

Anywhere on Scratch:

*Scratch: The coding language used on the website scratch.mit.edu, consisting of blocks used to build a script.

Sprite: The image or object that is shown on the screen and has the programming inside of it.

Script: A specific chunk of coding used to make a sprite do an action, such as moving across the screen.

Blocks: The connecting pieces with code inside used for making scripts in Scratch.

**Scratch: The website scratch.mit.edu.

***New Scratcher: The title used for users on the website

Scratcher: The title given to a New Scratcher once they have completed certain requirements.

Scratch Team/ST: The employees at Scratch who work on the site in different ways.

For the editor:

Extensions: Extra blocks for the Scratch editor that can be turned on for projects, including Pen and Text to Speech.

(There should be more, if there are any more, tell me!)

For the forums:

Subforum: A separate forum space for different topics.

Announcements: The subforum where the Scratch Team announces updates, Wiki Wednesdays, and other events.

****New Scratchers/NS: The subforum used for **New Scratchers to introduce themselves.

Help with Scripts/HwS: The subforum used for helping others program their projects.

Show and Tell/SaT: The subforum for users to show off their projects and studios to others.

Project Ideas/PI: The subforum for users to give and receive ideas for projects on Scratch.

Collaboration/Collab: The subforum for people working together on projects to talk.

Requests: The subforum for users looking to receive art, profile pictures, voice acting, and more.

Project Save and Level Codes/PSaLC: The subforum for users to store their progress on projects that have save codes.

Questions About Scratch/QaS: The subforum for general questions about the website Scratch.

Suggestions: The subforum for ideas on how to make Scratch better.

Bugs and Glitches/BaG: The subforum for reporting problems with the Scratch site.

Advanced Topics/AT: The subforum for talking about technical aspects, advanced features, or Scratch Modifications/Mods.

Connecting to the Physical World/CttPW: The subforum for topics related to Pico Boards, LEGO WeDo, and connecting Scratch to the physical world.

Developing Scratch Extensions/DSE: The subforum for users looking to get help making extensions for Scratch.

Open-Source Projects/OSP:The subforum for discussing Scratch's open-source projects.

Things I'm Making and Creating/TIMaC: The subforum for discussing things you are creating outside of the Scratch website.

Things I'm Reading and Playing/TIRaP: The subforum for discussing games, shows, or movies outside of the Scratch website.

These would be able to be toggled via your profile. They would be on by default. The toggle would say:
Scratch Definitions (on/off)

*The coding language used on the website scratch.mit.edu
**The website scratch.mit.edu
***Title for Scratchers who do not yet have the Scratcher title
****Subforum only
(Note that on a few of the forum notes, I had to copy/paste the definition on the forum page as I am almost only active on QaS and Suggestions, along with Bugs/Glitches when I can. I do not know the exact definition for some of the subforums.)

What if someone comments the following?

I'm doing an impromptu speech today! I'm basically starting from scratch. I'll be given a script around 10 minutes before my speech that I can use, just to help prevent any memory blocks from happening.

The underlined words are your given examples of words related to Scratch, but in the context of this comment, none of these words have anything to do with Scratch.

Dang, I posted a reply but it signed me out (it was supposed to, I was testing something, but it wasn't supposed to delete my post )

There could be a checkbox next to your forum post or comment before you post it that says, “Show Scratch Definitions”. If you un-check the box, it will not show the definitions with the words.