The WK is a bit witchy I suppose - he's one of the few characters in LOTR to use magic quite overtly. But anyone expecting the Nazgul to ride broomsticks or brew porions in couldrons, or keep cats or taods as pets, other witchy tropes: they are going to be disappointed.
Maybe it just sounded good & look no further?

Or maybe we have The Witch King in opposition ot the other main magic users, the Wizards?

Or maybe other forum members have better ideas?

The chief of these, the wielders of the Nine Rings, becomes the Witch-king of the realm of Angmar... ['The Tale of Years of the Third Age', HoMe XII]

But it was found later [after the fall of Angmar] that the Witch-king had fled away secretly southwards, and had entered Minas Ithil (now called Minas Morgul) and become Lord of the Ringwraiths. [The Heirs of Elendil', HoMe XII]

[Concerning an apparent shift in attitudes towards magic in the 15th Century, from scepticism to fear to a persecution.] One explanation offered by historian Michael D. Bailey is that at some point during the 14th and 15th centuries, religious officials perhaps unwittingly conflated two distinct traditions: “learned” magic and “common” magic. The common kind of magic required no formal training, was widely known, could be practised by both men and women, and was usually associated with love, sex and healing.
By contrast, learned magic came to Europe from the east and featured in the “magic manuals” that circulated among educated men whom Richard Kieckhefer described as members of a “clerical underworld”.
...
While men also feature in the infamous 15th century witch-hunting manual Malleus Maleficarum (The Hammer of the Witches), the work has long been recognised as deeply misogynistic. It suggests that women’s perceived lack of intelligence made them submissive to demons. One section reads:

Just as through the first defect in their [women’s] intelligence they are more prone to abjure the faith; so through their second defect of inordinate passions … they inflict various vengeances through witchcraft. Wherefore it is no wonder that so great a number of witches exist in this sex.

By the end of the Middle Ages, a view of women as especially susceptible to witchcraft had emerged.
...
The idea that women might have been dabbling with the demonic magic previously associated with educated males, however inaccurate it may have been, was frightening. Neither men nor women were allowed to engage with demons, but while men stood a chance at resisting demonic control because of their education, women did not.
Their perceived lack of intelligence, together with contemporary notions regarding their “passions”, meant that they were understood as more likely to make pacts of “fidelity to devils” whom they could not control – so, in the eyes of the medieval church, women were more easily disposed to witchcraft than men.


The evolution of the medieval witch – and why she’s usually a woman

by Dr J Farrell, Lecturer in Medieval History, University of Exeter

It was the Witch-king who summoned the Wights to inhabit the tombs of the Barrow-downs. Is that witchy enough?

Their name, as related to Wise, is an Englishing of their Elvish name, and is used throughout as utterly distinct from Sorcerer or Magician. [Letter 131]

There are no precise opposites to the Wizards - a translation (perhaps not suitable but throughout distinguished from other 'magician' terms)... [Letter 144]

It appeared that Gandalf had been to a great council of the white wizards, masters of lore and good magic; and that they had at last driven the Necromancer from his dark hold in the south of Mirkwood. ['The Last Stage']

To attempt to master them [Unbodied spirits] and to make them servants of one own's will is wickedness. Such practices are of Morgoth; and the necromancers are of the host of Sauron his servant.

Those who used the Nine Rings became mighty in their day, kings, sorcerers, and warriors of old.

In Rhudaur an evil folk, workers of sorcery, subjects of Angmar slay the remnants of the Dúnedain and build dark forts in the hills. ['The Heirs of Elendil', HoMe XII]

...but in Rhudaur for long there dwelt an evil people out of the North, much given to sorcery. ['The Tale of Years of the Third Age', HoMe XII]

'Few escape her [the "Lady in the Golden Wood's"] nets, they say. These are strange days! But if you have her favour, then you also are net-weavers and sorcerers, maybe.' ['The Riders of Rohan', LotR]

From Three Is Company:

It looked like the black shade of a horse led by a smaller All Black shadow. The All Black shadow stood close to the point where they had left the path, and it swayed from side to side. Frodo thought he heard the sound of scrum. The shadow bent to the ground, and then began to haka.
Once more the desire to tackle someone came over Frodo; but this time it was stronger than before. So strong that, almost before he realized what he was doing, his body crouched, ready to spring and fly: this time to tackle and then to hug.