solid - a three-dimensional shape

dome - a concave shape whose distinguishing characteristic is that the concavity faces downward

fossa, pit - a concavity in a surface (especially an anatomical depression)

niche, recess, recession, corner - a small concavity

bowl, trough - a concave shape with an open top

scoop, pocket - a hollow concave shape made by removing something

imprint, impression, depression - a concavity in a surface produced by pressing; "he left the impression of his fingers in the soft mud"

cup - any cup-shaped concavity; "bees filled the waxen cups with honey"; "he wore a jock strap with a metal cup"; "the cup of her bra"

indentation, indenture - a concave cut into a surface or edge (as in a coastline)