Heisenbug is a term used to describe a software bug that is difficult to replicate and often disappears when attempts are made to debug it. Synonyms for this elusive bug include ghost bug, phantom bug, and elusive bug. These terms are used interchangeably to describe the same issue that makes software developers pull their hair out. Similarly, the terms intermittent bug and non-deterministic bug are used to describe bugs that appear and vanish without any apparent pattern or reason. All these terms might be used to describe an unpredictable software bug, that appears and disappears, only to reappear unexpectedly, wreaking havoc on the system's functionality.