Deathreaten is a verb. It means the threat of death against someone; it also means to tell someone or others that you will murder them.
A: My son John told me yesterday that you deathreatened him!
B: Yes, it is true.
A: How dare you deathreaten my son, John?
B: Actually, I was so angry at that time. It was my mistake.
A: If you deathreaten him again then I will inform the police.
B: I am so sorry. I promise that I will never deathreaten your son again.