Definition - “A next-door neighbor, or a neighbor whose house is on fire” (Merriam-Webster’s Second New International Dictionary, 1934)
Ucalegon, in Trojan legend, was one of the counselors who sat with Priam, the king of Troy. His house, said to be situated next to Aeneas’, was set aflame when the city of Troy was taken by the Greeks.
Your home, my home, your neighbors home; they all have the potential to be engulfed in flames just fifteen minutes after a fire starts. The good news is that a grand total of one or two sprinklers usually controls a residential fire. If enough common sense prevails, the ucalegons of the future will have security through automatic protection.
— Mark Brennan, Common questions regarding residential fire sprinklers (in PM Engineer), Aug. 2000