The Chilko is the Chilcotin River's main tributary.

In fact at their confluence the Chilko River is much larger than the Chilcotin.

It is also the main reason why the lower reaches of the Chilcotin are very silty.

The meaning of the name is contested, and is the subject of much folk etymologising.

Due to a confused naming process, the name "Chilcotin River" refers to only the lower segment of Tŝilhqox, then follows a smaller tributary (Cheẑqox/Chezacut River) northwest to Chilcotin Lake (Cheẑich’ed Biny/Chezacut Lake), and then further north and west along another tributary (Yeqox Gunchagh or "big creek" in Tŝilhqot’in) to its nominal source.