Cól-þrǽd
Bosworth & Toller Anglo-Saxon Old English Dictionary - cól-þrǽd
According to the Old English Dictionary:
-þréd, es;
- cól-þrǽd
- m. A coal or blackened thread, plumb-line; perpendiculum :-- Cólþréd perpendiculum, Glos. Epnl. Recd. 160, 73. col-þræd