cyma vs cyma reversa

cyma and cyma reversa both are nouns.

Word	Noun	Adjective	Verb	Adverb
cyma	Yes	No	No	No
cyma reversa	Yes	No	No	No

As nouns, cyma reversa is a hyponym of cyma; that is, cyma reversa is a word with a more specific, narrower meaning than cyma:

cyma: (architecture) a molding for a cornice; in profile it is shaped like an S (partly concave and partly convex)
cyma reversa: a molding that (in section) has the shape of an S with the convex part above and the concave part below

Other hyponyms of cyma include cyma recta, ogee.

cyma (noun)	cyma reversa (noun)
(architecture) a molding for a cornice; in profile it is shaped like an S (partly concave and partly convex)	a molding that (in section) has the shape of an S with the convex part above and the concave part below