This is my page on the Joondeph surname.
Brest-Litovsk, Belarus: 1860s-1900s
New York City, USA: 1880s-1930s
Joondeph appears to be a contrived name. Possibly it is derived from Yiddish ‘yontef’ meaning “holiday”. Related names would be things like Yontev, Yontef, Yundow, etc.
The oldest known Joondephs are Samuel and Isaac. Depending on which records you believe, either one might be the elder. I think they are brothers, though this is not certain. Samuel was born in the 1860s and Isaac either the 1860s or 1870s.
Isaac and his wife Pauline (nee Sisselman) moved to New York City in the 1880s and had two children, Hyman and Rose, both born in the 1890s.
Samuel Joondeph married Anna (Hinde?) Yesnovski. The family immigrated to New York in the early 1900s. Their children were all born in Brest-Litovsk: Rebecca, Morris (Maurice), Charles, David, and Sophia.
Rebecca Joondeph married Abraham Miller and had three children, Estelle, Annette and Edwin.
Morris Joondeph died in his early 30s, I think as a bachelor.
Charles Joondeph married Anna Rabinowitz and had three children, Morris (Maurice), Jerome and Irene.
David Joondeph married Minnie and had a son named Norman who became a doctor in Connecticut.
Sophia Joondeph married Morris Friedberg.