Heuristic
A heuristic is an empirical usability rule used to quickly evaluate an interface, such as Nielsen's 10 heuristics.
Heuristics are general principles, like 'keep system status visible' or 'prevent errors rather than fix them'. They serve as a quick reading grid for an audit.
Without replacing full user testing, a heuristic evaluation quickly surfaces obvious friction: an inconsistent menu, an action with no visual feedback, an error message that makes no sense.