Early 20th century; earliest use found in The Monist: a quarterly magazine devoted to the philosophy of science. From the name of Bertrand Arthur William Russell + -ism.
Definition of Russellism in US English:
Russellism
nounˈrʌs(ə)lɪz(ə)m
The philosophical system of Bertrand Russell.
Origin
Early 20th century; earliest use found in The Monist: a quarterly magazine devoted to the philosophy of science. From the name of Bertrand Arthur William Russell + -ism.