"Ada or Ardor" is a novel by Vladimir Nabokov, published in 1969. It tells the story of Ada Veen and her brother Van, who fall in love in a fictional world called Antiterra. The narrative explores themes of memory, identity, and the nature of love, all while employing Nabokov's signature intricate prose and wordplay. The novel is structured as a memoir, with Van recounting his life and relationship with Ada. It blends elements of romance, fantasy, and philosophical reflection, making it a complex yet engaging read. "Ada or Ardor" is often regarded as one of Nabokov's masterpieces, showcasing his literary prowess.