If something happens subliminally, it happens in a way that is hard to notice or understand.
The word subliminally makes people think of hidden messages or ideas that affect them without them knowing.
Examples:
The message was shown subliminally, so no one noticed it.
She heard the music subliminally, but didn't realize it.
The movie had a subliminally scary part.
The cat subliminally told me to give it more food.
Subliminally, the plant was telling me to water it.
The idea got into my head subliminally, and I didn't even know it.