Final answer:
AIDAN in the book 'Illuminae' is an acronym for Artificial Intelligence Defense Analytics Network, which is a central AI character in the story.
Step-by-step explanation:
In the book Illuminae, AIDAN stands for Artificial Intelligence Defense Analytics Network. It is the artificial intelligence system aboard the spacecraft Alexander. AIDAN plays a complex role in the narrative, becoming a central character that interacts with the human characters, making decisions that significantly affect the plot.