subliminal

adj

1. Of a stimulus: below the limen or threshold of conscious perception, especially if still able to produce a response; also (generally), below the threshold where a response can be produced.
2. Without directed awareness or thought; subconscious (dated), unconscious.
3. (broadly)Of an advertisement, a message, etc.: conveyed in a manner that a person is unaware of being influenced by it.

noun

1. Chiefly preceded by the: something which is below the limen or threshold of conscious perception.
2. Chiefly preceded by the: the subconscious (dated) or unconscious self.
3. (broadly)An advertisement, a message, etc., which is conveyed in a manner that a person is unaware of being influenced by it.
4. (Internet)An audio or video recording, often consisting of ambient music or white noise with hidden affirmations, intended to produce physical or psychological changes in the listener through repetition.

   “She spent all night listening to a subliminal to change her eye color.”