In historical Germanic society,  ( ; ); was a term for a social stigma implying the loss of honour and the status of a villain. A person affected with the stigma is a  (/, , or ).
Middle English retained a cognate , meaning 'envy' (compare modern Dutch  and modern German ), 'hate', or 'malice'.

A related term is , carrying the connotation of 'unmanliness'.

Níð, argr, ragr and ergi
Ergi and argr or ragr can be regarded as specifying swearwords. Ergi, argr and ragr were the severe insults made by calling someone a coward, and due to its severity old Scandinavian laws demanded retribution for this accusation if it had turned out unjustified. The Icelandic Gray Goose Laws referred to three words that were regarded as equal to argr by themselves. Those were ragr, strodinn, and sordinn, all three meaning the passive role of a man in sexual activities, being womanly, and being subservient. Another semantic belonging to argr, ragr and ergi was, from the Gray Goose, "being a sorcerer's friend."

Examples from Old Scandinavian Laws: The Gulathing law referred to "being a male bottom," "being a thrall (slave)," "being a seiðmaðr (wizard)," the Bergen/Island law referred to "being a seiðmaðr," "being a sorcerer and/or desiring same-sex activities as a [passive] male (kallar ragann)," the Frostothing law to "desiring male same-sex activities as a bottom."
Thus, it is apparent that ergi of a níðingr was strongly connoted not only with sorcery, unmanliness, weakness, and effeminacy but also especially with lecherousness or sexual perversion in the view of Old Scandinavian people during the Early and High Middle Ages. Ergi of females was considered as excessive lecherousness bordering raging madness, ergi of males as perversity, effeminacy and the passive role within same-sex intercourse between men, while an active role of a man, who had been included into same-sex intercourse, was not tinged by ergi, ragr, argr or níð.

Scolding and níðstang

Níðings had to be scolded, i. e. they had to be shouted in their faces what they were in most derogatory terms, as scolding (Anglo-Saxon , Norse , Icelandic , OHG , Modern German ; compare scoff, Modern Dutch , Anglo-Saxon , and ) was supposed to break the concealing seiðr spell and would thus force the fiend to give away its true nature.

The actual meaning of the adjective  or  [Anglo-Saxon ] was the nature or appearance of effeminacy, especially by obscene acts.  was the worst, most derogatory swearword of all known to the Norse language. According to Icelandic law, the accused was allowed to kill the accuser without paying weregild.

If the accused did not retort by violent attack, either right on the spot or by demanding , yielding either the challenging accuser to take his words back or the accuser's death, he was hence proven to be a weak and cowardly  by not retorting accordingly.

Beside by words, scolding could also be performed by pejorative visual portrayals, especially by so-called níðstangs or nīþing poles. These were usually single poles with a carved man's head, on which a horse or a horse's head was impaled. In two attested instances (Bjarnar saga Hítdælakappa ch. 17, Gísla saga Súrssonar), two níðstangs were arranged so as to suggest homosexual intercourse.

A "classical definition of ergi is found in the scoldings (see section below) of opposing warriors Gudmund and Sinfyötli in the New Helgi song, offending each other as earg and thus challenging each other before a fight. Gudmund perjorates Sinfyötli in verse 36:

Verse 36
Prince you cannot
talk about me
like that,
scolding a
noble man.
For you ate
a wolf's treat,
shedding your brother's
blood, often
you sucked on wounds
with an icy maw,
creeping to
dead bodies,
being hated by all.

and in following verses 37-39 Sinfyötli rebuts this:

Verse 37
Walkury, an abhorrent
monster have you been
frightening, and earg,
by Odin!
The Einherjars
fought in desire
about you
stubborn whore.

Verse 38
Hag on Warinsey Island
that was you
so insidiously
conjuring illusions.
You said that
the only warrior
you desired to marry
was I, Sinfyötli.

Verse 39
On Sága's Inlet
you gave birth
to nine wolves
fathered by
Sinfyötli.

In accordance with these more detailed descriptions of what constituted  as appearing in the New Helgi song, the Gulathing law referred to eacans swearwords further describing  as "being a mare," "being a pregnant animal," "being a bitch," "having indecent intercourse with animals," the Bergen/Island law referred to "biting another man," "being a pregnant animal," the Frostothing law to "being a female animal," the Uplandslag law to "having sexual intercourse with an animal." It's worth to note that such activities as being "a pregnant animal" and having intercourse with animals are activities which are attributed to the god Loki in Lokasenna and Gylfaginning.

Nīþ and criminality

The seiðr used prominently by níðings was linguistically closely linked to botany and poisoning. Therefore, seiðr to a degree might have been regarded as identical to murder by poisoning. This Norse concept of poisoning based on magic was equally present in Roman law:

[The] equality in Germanic and Roman law about equalling poisoning and magic was not created by influence of Roman laws upon Germanic people, even though an identical conception was indeed manifest in Roman law. This apparent likeness is probably based upon the shared original primitive conceptions about religion due to a shared Indo-European origin of both people.

Níðing poisoning ties in with the legal Germanic differentiation of murder and killing. Criminal murder differed from legitimate killing as by being performed in secret insidiously, away from the eyes of the community that had not been involved in the matter.

Sorcery [in Norse antiquity] equalled mysteriously utilizing evil forces, just as mysterious and abhorrent a crime as sexual deviancy. As for theft and murder, even more recent common Old Scandinavian belief still regarded them to be so closely associated to magical practices as to be entirely impossible without these latter. Those that were capable of breaking open heavy locks at night without being noticed by watchdogs nor waking up people had to be in command of supernatural abilities. Equally weird were those that were capable of murdering innocent lives. They were aided, guided, or coerced by an evil force to do their evil deeds.

Since sorcery "was not accepted officially, it could not serve the kinship as a whole, only private cravings; no decent person was safe from the secret arts of sorcerers," and as nīþ was insidiousness, a níðing was also thought to be a pathological liar and an oathbreaker, prone to committing perjury and especially treason. Summing up the relations between nīþ and criminality:

Severe misdeeds were perjury deeds, especially if they had been committed insidiously and in secret. Such perpetrators were nithings, despicable beings. Their perjury deeds included: Murder, theft, nightly arson, as well as any deeds that harmed the kinship's legally protected rights (treason, deserting to the enemy, deserting from the army, resisting to fight in a war, and perversion). [Furthermore these deeds included] any crimes offending the deities, such as breaking a special peace treaty (for example thing peace, armistice, security of the ceremony places and buildings, or a special festivity peace), trespass, defilement of graves, sorcery, finally all perjury deeds indicating moral degeneration, such as oathbreaking, perversion, acts of nasty cowardness [i. e. any acts] of moral degeneration.

This excessive mass of níðing associations might at first seem cumbersome and without any recognizable pattern. However the pattern behind it is outlined in the following sections.

The immediate consequence of being proven a níðing was outlawing the exile. (see for example)

The outlawed did not have any rights, he was exlex (Latin for "outside of the legal system"), in Anglo-Saxon utlah, Middle Low German uutlagh, Old Norse utlagr. Just as feud yielded enmity among kinships, outlawry yielded enmity of all humanity.

"Nobody is allowed to protect, house, or feed the outlaw. He must seek shelter alone in the woods just like a wolf." "Yet that is but one aspect of outlawry. The outlaw is not only expelled from the kinship, he is also regarded henceforth as an enemy to mankind."

Ancient dehumanizing terms meaning both "wolf" and "strangler" were common as synonyms for outlaws: OHG warc, Salian wargus, Anglo-Saxon wearg, Old Norse vargr.

Outlaws were regarded as physically and legally dead, their spouse was seen as widow or widower and their children as orphans, their fortune and belongings were either seized by the kinship or destroyed. "It was every man's duty to capture the outlaw and [...] kill him."

Níðings were considered to re-enter their bodies after death by their seiðr magic and even their dead bodies themselves were regarded as highly poisonous and contagious. To prevent them from coming back as the undead, their bodies had to be made entirely immobile, especially by impaling, burning up, drowning in rivers or bogs (see also Tacitus), or even all of the above. "Not any measure to this end was considered too awkward."

It could be better to fixate the haunting evil's body by placing large rocks on it, impaling it [..]. Often enough, people saw their efforts had been in vain, so they mounted destruction upon destruction on the individual fiend, maybe starting by beheading, then entirely burning up its body, and finally leaving its ashes in streaming water, hoping to absolutely annihilate the evil, incorporeal spirit itself.

Nīþ and witchcraft

It was believed that the reason for a nīþing to resort to insidious seiðr "witchery" in order to cause harm instead of simply attacking people by decent, belligerent violence to achieve the same end was that it was a cowardly and weak creature, further indicating its being direct opposite of Old Norse warrior ethos. Earg is often but translated as "cowardly, weak". By definition, any seiðberender (practitioner of seiðr) was immediately rendered argr by these very despicable magic practices.

Nīþ did not only motivate practicing seiðr but was regarded the most likely motivation of all for practicing seid. The nīþing used its malicious seiðr magic to destroy anything owned and made by man, ultimately the human race and Midgard itself.Since primitive societies exclusively attributed their fear of evil sorcerers [i.e., seiðmaðr] to the sorcerer's motivating envy, all Indo-Germanic proverbs on the matter indicate that passive envy easily turns into aggressive crimes. He who envies is not satisfied to passively wait for his neighbours to run into accidents by coincidence to secretly gloat over them (while his gloating habits are widely accepted as a fact), he makes sure that they will live in misery or worse. […] Envy brings death, envy seeks evil ways.Hence, the nīþing was regarded as a mythological fiend "that only exists to cause harm and bring certain undoing." Harboring a nīþ was regarded as destroying the "individual qualities that constituted man and genetical relation," making deviant, perverse, and ill instead so that this fiend was considered the direct opposite of decent man and its [nīþ] as contagious.
[Nīþings] were aided, guided, or coerced by an evil force to do their evil deeds. Hence, a nithing was not only degenerated in a general [moral] sense [...] it had originally been a human being of evil, fiendish nature that had either sought evil deliberately or had been taken into possession by evil forces unwillingly.

Association with physical disability
Nithings were thought to be suffering of physical ailments and were associated with crippledness. Most notably were limping as an outer indication of being a nithing (such as in the story of Rögnvald Straightleg whose last name was in fact but an ironic offence as his legs were actually crippled), and the belief that sorcerers would not only give birth to animals but also to crippled human children.

[...] a nithing was not only degenerated in a general [moral] sense [...] This [moral] degeneration was often innate, especially apparent by physical ailments.

These physical afflictions were regarded as furthermore supporting weakness of a nithing. It was often hard to distinguish these attributes from actual physical illness, and since "any eeriness and incomprehensibility was what made people suspect a person of being a nithing, whether this was based upon physical anomalies or mental traits", they were often regarded as mentally ill even during ancient times already, as defined by actually or perceivedly deviant social behaviour and feeling.

Association with effeminacy
Nithings sometimes practiced seid in female clothes regardless of their biological sex, and they were considered to lose their physical biological sex by that act if they had been male before. More recent dialect forms of seid linguistically link it to "female sex organs." Also, there exists (or existed) evidence on the Golden Horns of Gallehus that male initiates of seid were ritually "effeminated" or made to appear "genderless" (such as by using "women's clothing" such as robes, as do priests of other religions, in order to manipulate the genderless spirits).

According eacans in the Gulathing law were "having born children as a male," "being a male whore," while the Gray Goose referred to "being a woman each ninth night," and "having born children as a male."

Runestones
Although no runic inscription uses the terms níð or níðingr, several Viking Age runestones use the term oníðingr, which with the o- prefix means the opposite of níðingr, to describe a man as being virtuous. Rundata translates this term as "unvillainous." This term is used as a descriptive term on runestones Ög 77 in Hovgården, Sö 189 in Åkerby, Sm 5 in Transjö, Sm 37 in Rörbro, Sm 147 in Vasta Ed, and DR 68 in Århus, and appears as a name or part of a name on inscriptions Ög 217 in Oppeby, Sm 2 in Aringsås, and Sm 131 in Hjortholmen. The same alliterative Old Norse phrase, manna mæstr oniðingR, which is translated as "the most unvillainous of men," appears on Ög 77, Sm 5, and Sm 37, and DR 68 uses a variant of this phrase.

See also
Hostis humani generis
Malakia in ancient Hellenic society (formerly Classical definition of effeminacy)
Moral turpitude
Raca in Semitic languages
Shame-stroke

References

Germanic paganism
LGBT in the Nordic countries
LGBT themes in mythology
Medieval LGBT history
Nid
LGBT and society
Sexuality in early Germanic culture
Homophobia
Violence against LGBT people
Social stigma