Like other terms borrowed from history, "euthanasia" has had different meanings depending on usage. The first apparent usage of the term "euthanasia" belongs to the historian Suetonius, who described how the Emperor Augustus, "dying quickly and without suffering in the arms of his wife, Livia, experienced the 'euthanasia' he had wished for."[9] The word "euthanasia" was first used in a medical context by Francis Bacon in the 17th century, to refer to an easy, painless, happy death, during which it was a "physician's responsibility to alleviate the 'physical sufferings' of the body." Bacon referred to an "outward euthanasia"—the term "outward" he used to distinguish from a spiritual concept—the euthanasia "which regards the preparation of the soul."[10]
In current usage, euthanasia has been defined as the "painless inducement of a quick death".[11] However, it is argued that this approach fails to properly define euthanasia, as it leaves open a number of possible actions which would meet the requirements of the definition, but would not be seen as euthanasia. In particular, these include situations where a person kills another, painlessly, but for no reason beyond that of personal gain; or accidental deaths that are quick and painless, but not intentional.[12][13]
Another approach incorporates the notion of suffering into the definition.[12] The definition offered by the Oxford English Dictionary incorporates suffering as a necessary condition, with "the painless killing of a patient suffering from an incurable and painful disease or in an irreversible coma",[14] This approach is included in Marvin Khol and Paul Kurtz's definition of it as "a mode or act of inducing or permitting death painlessly as a relief from suffering".[15] Counterexamples can be given: such definitions may encompass killing a person suffering from an incurable disease for personal gain (such as to claim an inheritance), and commentators such as Tom Beauchamp and Arnold Davidson have argued that doing so would constitute "murder simpliciter" rather than euthanasia.[12]
The third element incorporated into many definitions is that of intentionality – the death must be intended, rather than being accidental, and the intent of the action must be a "merciful death".[12] Michael Wreen argued that "the principal thing that distinguishes euthanasia from intentional killing simpliciter is the agent's motive: it must be a good motive insofar as the good of the person killed is concerned."[16] Similarly, Heather Draper speaks to the importance of motive, arguing that "the motive forms a crucial part of arguments for euthanasia, because it must be in the best interests of the person on the receiving end."[13] Definitions such as that offered by the House of Lords Select Committee on Medical Ethics take this path, where euthanasia is defined as "a deliberate intervention undertaken with the express intention of ending a life, to relieve intractable suffering."[2] Beauchamp and Davidson also highlight Baruch Brody's "an act of euthanasia is one in which one person ... (A) kills another person (B) for the benefit of the second person, who actually does benefit from being killed".[17]
Draper argued that any definition of euthanasia must incorporate four elements: an agent and a subject; an intention; a causal proximity, such that the actions of the agent lead to the outcome; and an outcome. Based on this, she offered a definition incorporating those elements, stating that euthanasia "must be defined as death that results from the intention of one person to kill another person, using the most gentle and painless means possible, that is motivated solely by the best interests of the person who dies."[18] Prior to Draper, Beauchamp and Davidson had also offered a definition that includes these elements. Their definition specifically discounts fetuses in order to distinguish between abortions and euthanasia:[19]
"In summary, we have argued ... that the death of a human being, A, is an instance of euthanasia if and only if (1) A's death is intended by at least one other human being, B, where B is either the cause of death or a causally relevant feature of the event resulting in death (whether by action or by omission); (2) there is either sufficient current evidence for B to believe that A is acutely suffering or irreversibly comatose, or there is sufficient current evidence related to A's present condition such that one or more known causal laws supports B's belief that A will be in a condition of acute suffering or irreversible comatoseness; (3) (a) B's primary reason for intending A's death is cessation of A's (actual or predicted future) suffering or irreversible comatoseness, where B does not intend A's death for a different primary reason, though there may be other relevant reasons, and (b) there is sufficient current evidence for either A or B that causal means to A's death will not produce any more suffering than would be produced for A if B were not to intervene; (4) the causal means to the event of A's death are chosen by A or B to be as painless as possible, unless either A or B has an overriding reason for a more painful causal means, where the reason for choosing the latter causal means does not conflict with the evidence in 3b; (5) A is a nonfetal organism."[20]
Wreen, in part responding to Beauchamp and Davidson, offered a six-part definition:
"Person A committed an act of euthanasia if and only if (1) A killed B or let her die; (2) A intended to kill B; (3) the intention specified in (2) was at least partial cause of the action specified in (1); (4) the causal journey from the intention specified in (2) to the action specified in (1) is more or less in accordance with A's plan of action; (5) A's killing of B is a voluntary action; (6) the motive for the action specified in (1), the motive standing behind the intention specified in (2), is the good of the person killed."[21]
Wreen also considered a seventh requirement: "(7) The good specified in (6) is, or at least includes, the avoidance of evil", although as Wreen noted in the paper, he was not convinced that the restriction was required.[22]
In discussing his definition, Wreen noted the difficulty of justifying euthanasia when faced with the notion of the subject's "right to life". In response, Wreen argued that euthanasia has to be voluntary, and that "involuntary euthanasia is, as such, a great wrong".[22] Other commentators incorporate consent more directly into their definitions. For example, in a discussion of euthanasia presented in 2003 by the European Association of Palliative Care (EPAC) Ethics Task Force, the authors offered: "Medicalized killing of a person without the person's consent, whether nonvoluntary (where the person in unable to consent) or involuntary (against the person's will) is not euthanasia: it is murder. Hence, euthanasia can be voluntary only."[23] Although the EPAC Ethics Task Force argued that both non-voluntary and involuntary euthanasia could not be included in the definition of euthanasia, there is discussion in the literature about excluding one but not the other.[22]