Chornyi [чорний ] means "black" and Ostriv [острів] means "island"

Some say the name Black Island comes from the region's marshy black soil; others say it's because the area used to be covered in forests of dense Durmast Oak trees (known for their dark wood); and still others claim that in the Middle Ages a plague swept through the town, almost wiping it out completely. The remaining citizens set the town on fire to cleanse any remnants of the sickness and they rebuilt it on the charred ruins, calling it Black Town.

Chornyi Ostriv is probably best known for the Przezdecki estate, which was built by Michal Przezdecki after taking ownership of Black Island in 1744. The estate was built using materials brought in from Italy and subsequent generations expanded it so that by the middle of the 1800's the estate had an impressive library, collections of antiques and paintings, and was host to many affluent artists and composers. 

Read about the comprehensive history of this region at the Internet Encyclopedia of Ukraine.

Geo-Political History

Searching records for specific years can be difficult without knowing exactly which administration the town was subject to at the time. Following is the list of different designations that you might find Chornyi Ostriv in starting with the most current. These are estimates, some of the changes remain unclear; for example in the summer of 1920, Chornyi Ostriv briefly was under Polish rule in the Podolian District.

Ukraine

Chornyi Ostriv settlement Hromada (municipality) :  Чорний Острів [Ukrainian]

within the Khmelnytskyi Raion (district) : Хмельницький район

within the Khmelnytskyi Oblast (province) : Хмельницька область

1938 - 1953 Ukrainian Soviet Socialist Republic (USSR, Soviet Union)

Cherny Ostrov Hromada (municipality)

within Khmelnytskyi Raion (district)

within Kamenets-Podolsk Oblast (province)

1922 - 1937 Ukrainian Soviet Socialist Republic (USSR, Soviet Union)

Cherny Ostrov

within Proskurov Okruha (county) : Проскурів oкруга

within Podolsk Oblast (province) : Подільська область

within Vinnytsia Raion (district) : Вінницький район

1793-1918 Russian Empire 

Cherno-Ostrov volost (subcounty) : Черно-Островская волость [Russian]

within the Proskurov uezd (county) : Проскуровский уезд

within the Podolia or Podolsk Guberniya (governate) : Подольская губерния

Prior to 1793 Polish-Lithuanian Commonwealth

Chornyi Ostriv was within the Podilia voivodeship : województwo podolskie [Polish]

within the Kingdom of Poland