Roget's Thesaurus of English Words and Phrases by Peter Mark Roget

indentation, intaglio, cavity, dent, dint, dimple, follicle, pit, sinus, alveolus†, lacuna; excavation, strip mine; trough &c (furrow) 259; honeycomb. cup, basin, crater, punch bowl; cell &c (receptacle) 191; socket. valley, vale, dale, dell, dingle, combe†, bottom, slade†, strath†, glade, grove, glen, cave, cavern, cove; grot†, grotto; alcove, cul-de- sac; gully &c 198; arch &c (curve) 245; bay &c (of the sea) 343. excavator, sapper, miner. honeycomb (sponge) 252.1. V. be concave &c adj.; retire, cave in. render concave &c adj.; depress, hollow; scoop, scoop out; gouge, gouge out, dig, delve, excavate, dent, dint, mine, sap, undermine, burrow, tunnel, stave in. Adj. depressed &c v.; alveolate†, calathiform†, cup-shaped, dishing; favaginous†, faveolate†, favose†; scyphiform†, scyphose†; concave, hollow, stove in; retiring; retreating; cavernous; porous &c (with holes) 260; infundibul†, infundibular†, infundibuliform†; funnel shaped, bell shaped; campaniform†, capsular; vaulted, arched. 252a Sponge — N. sponge, honeycomb, network; frit [Chem], filter. sieve, net, screen (opening) 260. Adj. cellular, spongy, spongious†; honeycombed, alveolar; sintered; porous (opening) 260.