subliminal

This term describes stimuli that are too weak or rapid to be consciously noticed but are still processed by the brain. It is most frequently used in psychological and marketing contexts to describe techniques intended to manipulate a person's desires or decisions without their knowledge.

While often associated with "hidden" messages in media, the word carries a clinical tone. It differs from "subconscious," which refers to the part of the mind where these processes occur, whereas "subliminal" refers specifically to the external stimulus itself.