The crime of killing one's grandson would typically be classified as "homicide." More specifically, if the act was intentional, it could be charged as "murder," while if it was unintentional, it might be classified as "manslaughter." The specific charges would depend on the circumstances surrounding the act, including intent and state laws.
"Homo" refers to human or mankind, while "cide" refers to the act of killing. When combined, the term "homicide" refers to the unlawful killing of one human by another.
The term for the killing of a student is "studentcide." It is a combination of the words "student" and "-cide," which means to kill.
"Homo" is a Latin prefix meaning "same" or "equal," often used in biological and social contexts to indicate similarity. "Cide," derived from the Latin "caedere," means "to kill" or "to cut down." Together, the term "homicide" refers to the act of killing a human being, encompassing various forms of unlawful killing, including murder and manslaughter.
The word suicide comes from two Latin words. It comes from sui which means oneself and cide which means killing. It is estimated the one million people commit suicide a year.
According to one source, Raphael Lemkin (1900-1959), a lawyer and a Polish Jew, coined the word genocide in 1943, in his book "Axis Rule in Occupied Europe". (Greek genopeople and Latin cide killing)
If you really need a relationship term, use granddaughter-in-law. Most people would merely say "my grandson's wife."
Regicide would be the specific term for killing a king. Assassination would also be appropriate for killing of any important figure, not just a king.
Your niece's son is your great-nephew. Your niece's grandson is your great-great nephew.
You are his great-great-aunt (or great-great-uncle) and he is your great-great-nephew.* A much less-used US term for the relationship is great-grandnephew which follows the logic that your niece's grandson is your sibling's great-grandson, so would have the same generation-separation from both you and your sibling.
I don't think there is a specific term, but I would suggest polytheocide.
There is no proper term for this particular familial place. I would suggest just his name or your step-father's grandson.
Socialization