ישו

Hebrew

From ישוע, itself from יהושע. There are two common explanations for the absence of the ayin:

Eruvin 53b:6-7 relates that Galileans did not distinguish the letters ayin, ḥet, he, and aleph, making the simplest explanation that this was a more accurate rendering of his name from the perspective of Judeans and Babylonians.^[1] Samaritan Hebrew continues to not distinguish these letters today, and Samaria is between Galilee and Judea. A pronunciation of Jesus's Syriac name ܝܫܘܥ without the ayin would render "yeshu".
Alternatively, it has been suggested that ישו is a deliberate pun on יש״ו. However, most religious Jews reserve yimákh shemó for people like Haman and Hitler.

It should be noted that:

Many individuals in the Talmud are called Yeshu, not all of whom can be the same person as their stories happen at very different times in Jewish history.^[2]
The name is found on one 1st-century ossuary, along with the more common Yeshua.^[3]

יֵשׁוּ • (yéshu) m

A name of several individuals in the Talmud and earlier works, found also on one 1st-century ossuary, equivalent to English Joshua or Jesus.
Jesus of Nazareth.

Used of Jesus the Nazarene in polemical contexts in the non-authoritative Toledot Yeshu, centuries after the first appearances of the name in the Talmud, in distinction from ישוע used of some other Joshuas, though most Joshuas are called יהושע.^[4]
In modern Hebrew, this is the standard secular spelling for Jesus of Nazareth.^[5]

^ Eruvin 53b.6 at Sefaria.
^ Berger, David (1998) “On the Uses of History in Medieval Jewish Polemic against Christianity: The Quest for the Historical Jesus”, in Carlebach, Elishiva, Efron, John M., Myers, David N., editors, Jewish History and Jewish Memory: Essays in Honor of Yosef Hayim Yerushalmi (The Tauber Institute for the Study of European Jewry)‎^[1], volume 29, Hanover, NH: Brandeis University Press, →ISBN, →LCCN, →OCLC, page 33: “Whatever one thinks of the number of Jesuses in antiquity, no one can question the multiplicity of Jesuses in Medieval Jewish polemic. Many Jews with no interest at all in history were forced to confront a historical/biographical question that bedevils historians to this day.”
^ (Please provide the book title or journal name)‎^[2], 2020 August 22 (last accessed), archived from the original on 17 July 2020
^ Robert E. Van Voorst, Jesus outside the New Testament, 2000, →ISBN, page 124.
^ Ben Yehuda Hebrew Dictionary, 1989, →ISBN, page 514. Bantam-Megiddo Hebrew Dictionary, 2009, page 177. Reuben Alcalay, 1963, The Complete Hebrew Dictionary, Masada Publishing Co., Ramat Gan, page 1995.

Yiddish Wikipedia has an article on:

ישו

Wikipedia ^yi

ישו • (yeyshu, yishu) m