selvedge

 
Pronunciation: /ˈsɛlvɪdʒ/
(chiefly North American also selvage)

noun

  • 1an edge produced on woven fabric during manufacture that prevents it from unravelling.
  • 2 Geology a zone of altered rock, especially volcanic glass, at the edge of a rock mass.

Origin:

late Middle English: from an alteration of self + edge, on the pattern of early modern Dutch selfegghe. The geological term dates from the 1930s