The Logoic plane (hyperplane or continuum/universe, enclosing and interpenetrating grosser planes, respectively) is the plane in which Brahman & Om or Aum, i.e. Logos or Agathon, i.e. (according to Theosophy) spirit of deity (as Brahman, Logos i.e. Agathon, etc.,) i.e. the creative Word (as the Pranava Om or Aum, Logos, Tikkun, etc.) and ideal, exists. The term is from the Greek word 'Logos' and is used in the Arcane School ideas.
'Classical' 1800s Theosophy does not say whether this spiritual plane is the only one that has to do with Logos is human, but Annie Besant & Charles Leadbeater may have said so, and Alice Bailey or others, who uses similar ideas, did say so.