convex

The English word 'convex' describes a surface or shape that curves outward, like the outside of a sphere. In Japanese, the most common equivalent is 凸面 (とつめん) or the adjective 凸状の (とつじょうの). However, depending on context, other expressions like 出っ張った (でっぱった) or 膨らんだ (ふくらんだ) may be more natural.