OCHRE, RED

o'-ker, (Isaiah 44:13, "He marketh it out with a pencil," margin "red ochre," the King James Version "line"; seredh, a word found only here, and of unknown etymology): Designates the implement used by the carpenter to mark the wood after measuring and before cutting. "Red ochre" supposes this to have been a crayon (as does "pencil"), but a scratch-awl is quite as likely. Ochre is clay colored by an iron compound.

From the International Standard Bible Encyclopedia
Edited by James Orr, published in 1939 by Wm. B. Eerdmans Publishing Co.