tracery

/T R EY1 S ER0 IY0/
noun
  1. 1

    Bars or ribs, usually of stone or wood, or other material, that subdivide an opening or stand in relief against a door or wall as an ornamental feature.

  2. 2

    A delicate interlacing of lines reminiscent of the architectural ornament.

Source: https://en.wiktionary.org/wiki/tracery