Desintegra means "disintegrates" or "falls apart". It's a strong and evocative verb that paints a vivid picture of something breaking down completely.
In the context of "Cozumel", Gustavo Cerati uses this word to describe a profound, almost surreal experience where "todo lo que viste se desintegra" (everything you saw disintegrates). It suggests a transformative journey where old perceptions and realities dissolve, leaving room for something new and unknown. This makes it a compelling word that hints at the song's mysterious atmosphere.