English edit

Etymology edit

sub- +‎ basement

Noun edit

subbasement (plural subbasements)

  1. A basement located beneath another basement
    • 2007 February 8, David W. Dunlap, “What May Have Made Good Neighbors Now Present a Puzzle”, in New York Times[1]:
      Joan H. Geismar is trying to unravel the mystery of old stone walls in the subbasement of Federal Hall National Memorial on Wall Street.