one who stubbornly adheres to traditional and outdated views.

one who vigorously defends an apparently hopeless position, a lost cause, etc.

stubbornly and vigorously resisting in the face of seemingly hopeless odds; as, diehard opposition.

Nickname of the Scottish Terrier.

DieHard automatically hardens software applications against a wide range of bugs. These bugs, known as memory errors, often end up as serious security vulnerabilities, cause crashes, or lead to unpredictable behavior. DieHard either eliminates these bugs altogether, or avoids them with high probability.

a pattern that eventually disappears, but takes a long time