convex
con-vex
adjective
Curving outwards like the exterior of a sphere or circle.
"The lens had a distinctly convex surface."
Thesaurus
Synonyms: umbellate, lenticular, umbel-like, gibbose, convexo-convex, lentiform, planoconvex, hogged, bell-shaped, biconvex, convexo-concave, bulging
Antonyms: concave