triglyph
A vertically channeled tablet of the Doric frieze.
An interesting architectural point is raised by some stone carvings, with a vertical triple-grooved design. So often is this design found that Mr. Fyfe, when discussing its occurrence on a miniature fresco at Knossos, calls it the most distinctive architectural ornament of the age. There is every probability that we may see in it the prototype of the "Triglyphs" that alternate with Metopes on the entablature of the Doric Temple.
Where it comes from
From Ancient Greek τρίγλυφος (trígluphos, “triglyph”).
Adapted from the Wiktionary entry triglyph (CC BY-SA 4.0).