Disabling the entire UI while in an inconsistent state, such as showing a throbber/loading bar during unexpectedly slow loading.
Wouldn’t that be a modal / blockingElement? And:
A slide show or “cover flow” style carousel may have non-active items partially visible, as a preview - they may be transformed or partially obscured to indicate that they are non-interactive.
Wouldn’t the “active item” here be a blockingElement of said non-active elements (ie. this also sounds like a modal)?