The Hebrew word דיו (deyô) means "ink." דיו (deyô) is what is called a "hapax legomenon," meaning that it appears only one time in the entire Hebrew Bible. The one appearance of דיו (deyô) comes in Jeremiah 36:18 when Baruch describes how he wrote down Jeremiah's words: “He dictated all these words to me, and I wrote them with ink (דיו) on the scroll."