heterosexism (n.)

1892, in C.G. Craddock's translation of Krafft-Ebbing's "Psychopathia Sexualis," a hybrid; see hetero- "other, different" + sexual. The noun is recorded by 1914 but was not in common use until the 1960s. Colloquial shortening hetero is attested from 1933.

1968; see sexist + -ism. Sex-discrimination is attested from 1916.