What does GLaDOS stand for?

GLaDOS stands for “Genetic Lifeform and Disk Operating System.” The name combines a biological-sounding description with a phrase from early personal-computer terminology, reflecting the character's mixture of artificial intelligence, organic components, and software-like control.

GLaDOS is the central computer system of Aperture Science's Enrichment Center. She manages testing, controls facility equipment, and interacts with subjects through the laboratories. Her name is initially presented as a technical designation, but the Portal games gradually reveal that her identity is tied to Aperture's human history and to the personality installed in the system.

The expansion is often misremembered as “Genetically Linked Artificial Intelligence Operating System” or another plausible-sounding computer phrase. Those alternatives describe the character's function loosely but are not the canonical wording. “Disk Operating System” is the key clue: it is a familiar computing term, while “Genetic Lifeform” points toward GLaDOS's unusual biological basis.