subjective

Formed, as in opinions, based upon a person's feelings or intuition, rather than upon observation or purely logical reasoning; coming more from within the observer than from observations of the external environment.

Pertaining to subjects as opposed to objects (A subject is one who perceives or is aware; an object is the thing perceived or the thing that the subject is aware of.)

Resulting from or pertaining to personal mindsets or experience, arising from perceptive mental conditions within the brain and not necessarily or directly from external stimuli.

Economics is a messy discipline: too fluid to be a science, too rigorous to be an art. Perhaps it is fitting that economists’ most-used metric, gross domestic product (GDP), is a tangle too.[…]But as a foundation for analysis it is highly subjective: it rests on difficult decisions about what counts as a territory, what counts as output and how to value it. Indeed, economists are still tweaking it.

Lacking in reality or substance.

As used by Carl Jung, the innate worldview orientation of the introverted personality types.

The subjective case.

A noun or pronoun in the subjective case.