Curvaceous is a word used to describe a person or an object having shapely curves or contours, usually referring to a woman's body. Some antonyms for curvaceous would be words like angular or sharp-edged, which describe something having pointed or hard edges. Other antonyms might include words like gaunt, which refers to someone being thin or emaciated in a way that lacks curves or curves in the wrong places. Some people might also use words like flat or straight to describe something that lacks curves or angles, but these words can be a bit ambiguous and may not be the best fit for this particular concept.