1.  concavity(n = noun.shape) concave shape, incurvation, incurvature - a shape that curves or bends inward;
is a kind of solid
has particulars: dome, fossa, pit, corner, niche, recess, recession, bowl, trough, pocket, scoop, depression, impression, imprint, cup, indentation, indenture
Derived form adjective concave₁

2.  concavity(n = noun.attribute) concaveness - the property possessed by a concave shape;
is a kind of configuration, conformation, contour, form, shape
has particulars: hollowness
Derived form adjective concave₁

   A concave surface, or the space bounded by it; the state of being concave. [1913 Webster]

N  concavity, depression, dip, hollow, hollowness, indentation, intaglio, cavity, dent, dint, dimple, follicle, pit, sinus, alveolus, lacuna, excavation, strip mine, trough, honeycomb, cup, basin, crater, punch bowl, cell, socket, valley, vale, dale, dell, dingle, combe, bottom, slade, strath, glade, grove, glen, cave, cavern, cove, grot, grotto, alcove, cul-de- sac, gully, arch, bay, excavator, sapper, miner, honeycomb (sponge), depressed, alveolate, calathiform, cup-shaped, dishing, favaginous, faveolate, favose, scyphiform, scyphose, concave, hollow, stove in, retiring, retreating, cavernous, porous, infundibul, infundibular, infundibuliform, funnel shaped, bell shaped, campaniform, capsular, vaulted, arched.