My mother’s father was born David Joskowicz in 1901 in Pultusk, Poland, near Warsaw. “Joskowicz” is pronounced like “Yiskovitch”. He was one of 12 known (or theorized) children of Isaac and Marya nee Zarywacz. 8 of the children and the parents emigrated to the United States between 1905 and 1920. The other 4 children died at young ages. They settled in the Philadelphia area.
All of the Joskowicz family members changed their names to Jacobs after arriving in America, generally when they were naturalized. The 8 Jacobs children went on to have 35 children of their own, of whom about 10 are still alive. Those 35 have had 69 2nd generation Americans, including myself. The Joskowicz/Jacobs family has truly thrived.
The father of Isaac Joskowicz was Jojna Joskowicz. Jojna’s father was Josko. I believe that the name Joskowicz was first used by Jojna, with Joskowicz meaning “son of Josko”. It was then passed down as the family name from that point on, until it was changed to Jacobs in America.