roulette vs curved shape

roulette and curved shape both are nouns.

Word	Noun	Adjective	Verb	Adverb
roulette	Yes	No	No	No
curved shape	Yes	No	No	No

As nouns, curved shape is a hypernym of roulette; that is, curved shape is a word with a broader meaning than roulette:

roulette: a line generated by a point on one figure rolling around a second figure
curved shape: the trace of a point whose direction of motion changes

Other hypernyms of roulette include curve.

roulette (noun)	curved shape (noun)
a gambling game in which players bet on which compartment of a revolving wheel a small ball will come to rest in	the trace of a point whose direction of motion changes
a wheel with teeth for making a row of perforations
a line generated by a point on one figure rolling around a second figure