There are several synonyms for the phrase "killing by electric shock." These include electrocution, electro-execution, electric homicide, and shock execution. These terms are often used to describe the act of killing someone through the use of electric current. While electrocution is the most commonly used term, the others are also used in certain contexts and can be found in legal and medical documents. It is important to note that all of these terms refer to a violent and often traumatic form of death, and they should be used with sensitivity and care in any context.