stereotype (n.)

1798, "method of printing from a plate," from French stéréotype (adj.) "printed by means of a solid plate of type," from Greek stereos "solid" (see stereo-) + French type "type" (see type (n.)).

The meaning was extended to the stereotype plate itself by 1817. The plate saves time and effort as it duplicates, in a single piece of type-metal, the face of a page of types composed by hand for printing.

Hence the figurative meaning "image perpetuated without change" (such as a visual trope or oft-repeated expression; compare cliche), which is recorded by 1850, perhaps via the verb in this sense (which is by 1819).

The specific meaning "preconceived and oversimplified notion of characteristics typical of a person or group" is recorded by 1922 (Walter Lippmann, "Public Opinion").

1804, "to cast a stereotype plate," from stereotype (n.). It is attested by 1819 in the figurative sense of "fix firmly or unchangeably," and by 1953 specifically as "assign preconceived and oversimplified notion of characteristics typical of a person or group." Related: Stereotyped; stereotyper; stereotyping; stereotypy.