THESAURUS
retreating
boat-shaped, boatlike, bowl-shaped, bowllike, cavelike, cavernous, concave, concaved, craterlike, cup-shaped, cupped, cymbiform, declining, diminishing, dish-shaped, dished, dishing, dishlike, dwindling, dying, ebbing, fading, funnel-breasted, funnel-chested, funnel-shaped, hollow, hollowed, incurved, incurving, incurvous, infundibular, infundibuliform, navicular, naviform, receding, retiring, saucer-shaped, scaphoid, scyphate, shrinking, sinking, spoonlike, sunk, sunken, waning
ROGET THESAURUS
retreating
Concavity
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.