Why was "tantrum" trending last week?
1640s, "treating of a thing as the same as another," from French identification, probably from identifier (see identify). Sense of "becoming or feeling oneself one with another" is from 1857. Sense of "determination of identity" is from 1859. Meaning "object or document which marks identity" is from 1947 (short for identification tag, card, etc.).
identification i·den·ti·fi·ca·tion (ī-děn'tə-fĭ-kā'shən)
A person's association with the qualities, characteristics, or views of another person or group.
An unconscious process by which a person transfers the response appropriate to a particular person or group to a different person or group.