Queried GO term:

  idGO:0043233   Detailed information
  nameorganelle lumen
  namespacecellular_component
  def"The internal volume enclosed by the membranes of a particular organelle; includes the volume enclosed by a single organelle membrane, e.g. endoplasmic reticulum lumen, or the volume enclosed by the innermost of the two lipid bilayers of an organelle envelope, e.g. nuclear lumen." [GOC:jl, GOC:mah]
  is_aGO:0031974 ! membrane-enclosed lumen
  is_aGO:0044422 ! organelle part

No monarch genes has the input GO term: GO:0043233.