Douglas Harper's Etymology Dictionary
1880, noun of action from subjectify.
Wikipedia
In historical (or diachronic) linguistics, subjectification (also known as subjectivization or subjectivisation) is a language change process in which a linguistic expression acquires meanings that convey the speaker's attitude or viewpoint. This is a pragmatic-semantic process, which means that inherent as well as contextual meaning of the given expression is considered. Subjectification is realized in lexical and grammatical change. It is also of interest to cognitive linguistics and pragmatics (cf. Ronald Langacker and Elizabeth Traugott).
Usage examples of "subjectification".
As the walls of these institutions break down, the logics of subjectification that previously operated within their limited spaces now spread out, generalized across the social field.