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Webster 1828 Edition

Noun.

Ornamental stone work.

tracery ‎(plural traceries)

(architecture) 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.
A delicate interlacing of lines reminiscent of the architectural ornament.
- 1881, Robert Louis Stevenson, Virginibus Puerisque:
  He is homesick for the hale rough weather; for the tracery of the frost upon his window-panes at morning, the reluctant descent of the first flakes, and the white roofs relieved against the sombre sky.