Severity
How much damage a bug does to the product or the user.
Definition
Severity describes the impact of a bug on the system or user: for example blocker or critical (crash, data loss, no workaround), major, minor or trivial (cosmetic). The tester usually proposes it, and it is confirmed or adjusted in triage. It is independent of how soon the bug will be fixed.
In practice
The app crashes on launch for all users: critical severity. A slightly misaligned icon: low severity.
Learn it in context
Lessons that use this term.