I've been using this term a lot lately, and I'm honestly not sure how many people know it. I feel like it's self-explanatory enough that when I use it, people will pick up on what it is based on the context even if they don't know.
But essentially, your mindform is your inner world body.
You can close your eyes and imagine yourself sitting in a chair. Some people will imagine themselves from a third person perspective, in which case your mindform is whatever you see sitting there. If you are imagining from a first-person perspective, then imagine a mirror in front of you. Whatever you see in the mirror is your mindform.
Because this is happening in your head, you should be able to change the mindform at will. Imagine yourself bigger or smaller. Change into a completely different creature.
I think mindforms are most useful as a concept when we are talking about systems because systems tend to use their mindforms more often to interact with headmates.
But they importantly are not exclusive to systems. Most singlets should also have mindforms, but their default mindforms are usually just going to look similar to their body unless they are experiencing some form of alterhumanity that makes them see themselves as something else. Or maybe a closeted trans person might imagine themselves looking like their true selves.
After looking at Google, the words "default mindform" have apparently never been used together in human history. So I guess this is also a coining post of sorts.
Anyway, the default mindform is just the form someone frequently defaults to. It's the one they identify with and feel comfortable with, and some may experience dysphoria if they take a different form.
Most of the time, I have a tendency to use these interchangeably, but I do want to make this distinction because headmates are not actually locked to one form. You can change your mindform to try out different appearances the same way you can try on different clothes.
So the mindform is more nebulous. It is whatever you appear as at that given moment. But the default mindform is what you identify with. It is who you are internally beneath the body's meatsuit.
And I will also add that some headmates have multiple default mindforms. There may be multiple appearances they feel comfortable adopting. There's not a limit on how many default mindforms you can have.
