cyma recta vs cymatium

cyma recta and cymatium both are nouns.

Word	Noun	Adjective	Verb	Adverb
cyma recta	Yes	No	No	No
cymatium	Yes	No	No	No

As nouns, cymatium is a hypernym of cyma recta; that is, cymatium is a word with a broader meaning than cyma recta:

cyma recta: a cyma in which the upper section is concave and the lower section is convex
cymatium: (architecture) a molding for a cornice; in profile it is shaped like an S (partly concave and partly convex)

Other hypernyms of cyma recta include cyma.

cyma recta (noun)	cymatium (noun)
a cyma in which the upper section is concave and the lower section is convex	(architecture) a molding for a cornice; in profile it is shaped like an S (partly concave and partly convex)