There are 2 main definitions of Ob in English:

Ob1

Line breaks: Ob
The principal river of the western Siberian lowlands and one of the largest rivers in Russia. Rising in the Altai Mountains, it flows generally north and west for 5,410 km (3,481 miles) before entering the Gulf of Ob (or Ob Bay), an inlet of the Kara Sea, a part of the Arctic Ocean.

Definition of Ob in: