1936, U.S. colloquial, from curve (n.) + facetious use of -aceous, the Modern Latin botanical suffix meaning "of a certain kind." First recorded reference is in "Screen Book" magazine, writing of Mae West.
1690s, "curved line, a continuous bending without angles," from curve (v.). With reference to the female figure (usually plural, curves), from 1862; in reference to statistical graphs, by 1854; as a type of baseball pitch that does not move in a straight line, from 1879. An old name for it was slow. "Slows are balls simply tossed to the bat with a line of delivery so curved as to make them almost drop on the home base." [Chadwick's Base Ball Manual, 1874]
word-forming element denoting "belonging to, of the nature of," from Latin -aceus, enlarged form of adjectival suffix -ax (genitive -acis); see -acea. Especially in biology, "pertaining to X order of plants or animals."
<a href="https://www.etymonline.com/word/curvaceous">Etymology of curvaceous by etymonline</a>
Harper, D. (n.d.). Etymology of curvaceous. Online Etymology Dictionary. Retrieved $(datetime), from https://www.etymonline.com/word/curvaceous