What speakers mean by it
In English, york is first a place-name: the city in northern England, then a family of copies on other maps, a royal dukedom, and the late-medieval House of York. Written in lower case, it is also a cricket verb. To york a batter is to bowl a yorker, a ball that pitches at the toes and is awkward to play. Both the city-name and the sporting verb sit on the same short spelling. The origin of the word york is older than either of those later uses, and it is not a native English coinage. It is a Brittonic name that Romans latinized, Anglian speakers recast as a boar-town, and Norse speakers shortened until English borrowed the clipped form.
A Celtic name in a Roman city
The earliest written shape is not English. In the second century the geographer Ptolemy listed the site as Eborakon. Roman writers and inscriptions used Eboracum or Eburacum for the legionary fortress and later colonia founded in the late first century at the meeting of the Ouse and the Foss. Those endings are Greek and Latin. The stem is Brittonic, reconstructed as something like *Eburācon, the ancestor of Welsh Efrog.
Two readings of that stem are both current, and the evidence does not pick a winner. One takes the first element as Proto-Celtic *eburos, a word for the yew, plus a suffix *-ākon that marked a place belonging to or associated with something. On that view the name meant a yew estate or a settlement of yews. The other reading treats Eburos as a personal name built from the same plant-word, so the place would be the property of a man called Eburos. Names of this type are common in Gaul, and many of them do go back to a person rather than a tree, which is why some place-name scholars lean that way. Handbooks still print both. A twelfth-century story that a king Ebraucus founded the city is a later legend, not an independent clue.
Plant-words related to *eburos survive outside English: Old Irish ibar and modern Irish iúr for yew, and Breton evor for a related shrub. Irish Eabhrac and Scottish Gaelic Eabhraig keep a form of the latinized city-name rather than the Norse clipping. Cornish Evrek and Welsh Caerefrog likewise continue the Brittonic line.
How Old English made a boar-town
After Roman administration faded, speakers of Old English rebuilt the name as Eoforwīc. They matched the first part to eofor, wild boar, and added wīc, a word used in this period for a settlement, often one with a Roman past or a market. The result is folk etymology, not a translation of yew. A Brittonic yew-place became, in Anglian mouths, boar-town. The Germanic root behind eofor is *eburaz, which happens to look a little like Celtic *eburos, so the mishearing was easy. Written Old English forms such as Eoforwic and Eoforwicceaster appear from about the late ninth century into the twelfth.
That native English name did not drop at once. Middle English still had Everwik, Everwich, and close spellings beside the newer short form. Those descendants of Eoforwīc went out of ordinary use after the fifteenth century. Church Latin never fully dropped the Roman name either: the Archbishop of York still signs as Ebor, a fossil of Eboracum sitting beside the everyday English word.
The Norse cut that English kept
In 866 a Danish army took the city. Scandinavian speakers adapted Eoforwīc to Jórvík, earlier Éorvík. The initial consonant was a y-sound, so speech already leaned toward the modern English shape. The first element may have been felt as Old Norse jór, horse, or lined up with a boar-word matching English eofor. The second could be heard as vík, inlet, even though the site is not a bay. Later Icelandic also has the contracted Jórk. That short Norse form, not the Old English one, is the immediate source of Middle English York, Ȝork, and Ȝorc. The spelling York is in English use from the thirteenth century.
Icelandic still uses Jórvík for the English city, which shows that the Viking name was a living word, not a modern reconstruction. Several places in Iceland were themselves named Jórvík from it in the tenth or eleventh century.
Senses that grew from the city-name
Once York was the ordinary English name of the city, it spread as a habitational surname, as the title Duke of York, and as the House of York in the Wars of the Roses, whose badge was the white rose. Emigrants and officials copied it onto maps from Pennsylvania to Western Australia. New York is the most famous of those transfers, a Dutch-then-English colony renamed for the duke, not for the northern English city in a direct geographical sense.
The cricket sense is later and less settled in detail. Yorker as a delivery is in print by the 1860s. The verb to york is a back-formation from that noun, with evidence from 1882. One explanation is simply geographic: Yorkshire bowlers were said to use the ball often. Another points to older slang in which to come Yorkshire over someone, or to york a person, meant to cheat or overreach, which would fit a ball meant to deceive the bat. Both remain guesses. A separate slang verb york, to vomit, is sometimes called imitative and does not belong in the place-name chain.
A sibling that never met the Vikings
Portuguese Évora goes back to a related Celtic *Ebora, latinized as Ebora, from the same yew-word. English York and Portuguese Évora are distant doublets: two towns named from one Celtic root, one reshaped by Anglian folk etymology and then clipped in Norse, the other not. The short English spelling is that Viking clip of a recast Roman city-name that began as a Brittonic yew-place, or as the estate of a man named for the yew. Welsh Efrog still shows the path that English did not take.