User blog comment:B214/Question and Answers 6/@comment-168.28.156.112-20170124171527/@comment-9595671-20170125135938

Yeah, plus series like UQ Holder are more recent ones that show Immortality isn't the same as being unkillable, just extremely hard to kill.

The usual definition to people for what being immortal is would be more accurate as being invincible or invulnerable, being unable to die and being unable to be harmed.