The word is over a thousand years old: Old English formed the compound wiccecræft from wicce ('witch') and cræft ('craft'). The masculine form was wicca ('male sorcerer').

According to the Oxford English Dictionary, wicce and wicca were probably derived from the Old English verb wiccian, meaning 'to practice witchcraft'. Wiccian has a cognate in Middle Low German wicken (attested from the 13th century). The further etymology of this word is problematic. It has no clear cognates in other Germanic languages outside of English and Low German, and there are numerous possibilities for the Indo-European root from which it may have derived.

Another Old English word for 'witch' was hægtes or hægtesse, which became the modern English word "hag" and is linked to the word "hex". In most other Germanic languages, their word for 'witch' comes from the same root as these; for example German Hexe and Dutch heks.

In colloquial modern English, the word witch is particularly used for women. A male practitioner of magic or witchcraft is more commonly called a 'wizard', or sometimes, 'warlock'. When the word witch is used to refer to a member of a neo-pagan tradition or religion (such as Wicca), it can refer to a person of any gender.

Witches are commonly believed to cast curses; a spell or set of magical words and gestures intended to inflict supernatural harm. Cursing could also involve inscribing runes or sigils on an object to give that object magical powers; burning or binding a wax or clay image (a poppet) of a person to affect them magically; or using herbs, animal parts and other substances to make potions or poisons. Witchcraft has been blamed for many kinds of misfortune. In Europe, by far the most common kind of harm attributed to witchcraft was illness or death suffered by adults, their children, or their animals. "Certain ailments, like impotence in men, infertility in women, and lack of milk in cows, were particularly associated with witchcraft". Illnesses that were poorly understood were more likely to be blamed on witchcraft. Edward Bever writes: "Witchcraft was particularly likely to be suspected when a disease came on unusually swiftly, lingered unusually long, could not be diagnosed clearly, or presented some other unusual symptoms".

A common belief in cultures worldwide is that witches tend to use something from their target's body to work magic against them; for example hair, nail clippings, clothing, or bodily waste. Such beliefs are found in Europe, Africa, South Asia, Polynesia, Melanesia, and North America. Another widespread belief among Indigenous peoples in Africa and North America is that witches cause harm by introducing cursed magical objects into their victim's body; such as small bones or ashes. James George Frazer described this kind of magic as imitative.

In some cultures, witches are believed to use human body parts in magic, and they are commonly believed to murder children for this purpose. In Europe, "cases in which women did undoubtedly kill their children, because of what today would be called postpartum psychosis, were often interpreted as yielding to diabolical temptation".

Witches are believed to work in secret, sometimes alone and sometimes with other witches. Hutton writes: "Across most of the world, witches have been thought to gather at night, when normal humans are inactive, and also at their most vulnerable in sleep". In most cultures, witches at these gatherings are thought to transgress social norms by engaging in cannibalism, incest and open nudity.

Witches around the world commonly have associations with animals. Rodney Needham identified this as a defining feature of the witch archetype. In some parts of the world, it is believed witches can shapeshift into animals, or that the witch's spirit travels apart from their body and takes an animal form, an activity often associated with shamanism. Another widespread belief is that witches have an animal helper. In English these …

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Most societies that have believed in harmful or black magic have also believed in helpful or white magic. Where belief in harmful magic is common, it is typically forbidden by law as well as hated and feared by the general populace, while helpful or apotropaic (protective) magic is tolerated or accepted by the population, even if the orthodox establishment opposes it.

In these societies, practitioners of helpful magic provide (or provided) services such as breaking the effects of witchcraft, healing, divination, finding lost or stolen goods, and love magic. In Britain, and some other parts of Europe, they were commonly known as 'cunning folk' or 'wise people'. Alan Macfarlane wrote that while cunning folk is the usual name, some are also known as 'blessers' or 'wizards', but might also be known as 'white', 'good', or 'unbinding witches'. Historian Owen Davies says the term "white witch" was rarely used before the 20th century. Ronald Hutton uses the general term "service magicians". Often these people were involved in identifying alleged witches.

Such helpful magic-workers "were normally contrasted with the witch who practiced maleficium—that is, magic used for harmful ends". In the early years of the European witch hunts "the cunning folk were widely tolerated by church, state and general populace". Some of the more hostile churchmen and secular authorities tried to smear folk-healers and magic-workers by falsely branding them 'witches' and associating them with harmful 'witchcraft', but generally the masses did not accept this and continued to make use of their services. The English MP and skeptic Reginald Scot sought to disprove magic and witchcraft altogether, writing in The Discoverie of Witchcraft (1584), "At this day, it is indifferent to say in the English tongue, 'she is a witch' or 'she is a wise woman'". Historian Keith Thomas adds "Nevertheless, it is possible to isolate that kind of 'witchcraft' which involved the employment (or presumed employment) of some occult means of doing harm to other people in a way which was generally disapproved of. In this sense the belief in witchcraft can be defined as the attribution of misfortune to occult human agency".

Emma Wilby says folk magicians in Europe were viewed ambivalently by communities, and were considered as capable of harming as of healing, which could lead to their being accused as malevolent witches. She suggests some English "witches" convicted of consorting with demons may have been cunning folk whose supposed fairy familiars had been demonised.

Hutton says that magical healers "were sometimes denounced as witches, but seem to have made up a minority of the accused in any area studied". Likewise, Davies says "relatively few cunning-folk were prosecuted under secular statutes for …

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