triglyph
noun
tri·glyph ˈtrī-ˌglif 
: a slightly projecting rectangular tablet in a Doric frieze with two vertical channels of V section and two corresponding chamfers or half channels on the vertical sides
triglyphic
trī-ˈgli-fik
adjective or triglyphical
trī-ˈgli-fi-kəl
Word History
Etymology
Latin triglyphus, from Greek triglyphos, from tri- + glyphein to carve — more at cleave
First Known Use
1563, in the meaning defined above