From a primitive root meaning to engrave; a chisel or graver; also a style for writing -- graving tool, pen.
H2747. cheret
חֶ֫רֶט noun [masculine] graving-tool, stylus —
1 graving-tool, with which Aaron fashioned (וַיָּצַר) the molten calf Exodus 32:4 (E).
2 stylus, for writing on tablet (גִּלָּיוֺן): אֱנוֺשׁ בְּחֶרֶט עָלָיו כְּתֹב Isaiah 8:1 write on it with a man's (i.e. an ordinary) stylus = in common characters, intelligible to all (see BenzArchaeology 290).