A skookum is a variety of mountain giant or monster similar to the Sasquatch or Bigfoot. In the surviving Chinuk-Wawa spoken in Grand Ronde, Oregon, this variant is pronounced differently - skoo-KOOM, but when used in English with this meaning, it is pronounced the same way as the "big and strong" meaning.
Skookums were bad spirits or devils of which crows, eagles, owls, blue jays, various beasts and reptiles could be representations. They could inhabit people and cause serious illness.
The Chinook has several names for a bigfoot-type monster, depending on gender and location. The most famous, Skookum, is translated as "Evil God of the Woods" or mountain devil. Other terms include Itohiul (big feet).