The word "euthanasia" comes from the Greek -- "eu" meaning "goodly or well" + "thanatos" meaning "death." So, euthanasia is literally the "good death."
In 18th-century England, that was what euthanasia meant, a "good" death, a welcome way to depart quietly and well from life. Today the most commonly understood meaning of euthanasia is more than this old dictionary definition of dying well a good and easy death. Euthanasia refers, for example, to the situation when a doctor induces the death with a lethal injection, of a patient who is suffering unrelievedly and has persistently requested the doctor to do so.
Suicide, whether irrational or rational, for unrelated reasons is not euthanasia. Nor is euthanasia the forced killing of another person.
Human euthanasia is legal in the Netherlands, Belgium, Colombia, and Luxembourg (while assisted suicide is legal in Switzerland, Germany, Japan, Canada, and in the US). Euthanasia is the intentional termination of life by somebody other than the person concerned at his or her request. Assisted suicide means intentionally helping a patient to terminate his or her life at his or her request. Euthanasia is the termination of life by a doctor at the express wish of a patient. The request to the doctor must be voluntary, explicit and carefully considered and it must have been made repeatedly. Moreover, the patient's suffering must be unbearable and without any prospect of improvement.
Pain relief administered by a doctor may shorten a patient's life. As is the case in these other countries, this is seen as a normal medical decision in terminal care and not as euthanasia.
Conclusion: Euthanasia is a matter of continuing controversy, a tinderbox for debate, an issue on which positions range widely and include enthusiastic advocacy of euthanasia, guarded acceptance of euthanasia, outright rejection of euthanasia, and vehement condemnation of euthanasia, equating it with murder, genocide, or worse. But who knows? Euthanasia is an area in which honest people may still differ.