concavities
Bowl-shaped surface features
Concavities are surfaces or spaces that curve inward, like the inside of a bowl or sphere.
The word appears in technical and formal contexts—architecture, mathematics, anatomy—where the shape of hollows matters: the concavities of the skull, the gentle concavities of the landscape.
The opposite quality, curving outward, is convexity.
Empty space within
- voidWithout legal effect
- pitFruit's hard seed
- craterImpact or volcanic basin
- basinConcave water receptacle
depression · trough · dip · sinkhole · cenote · caldera · crater lake · pothole
Hollow receiving cavity
- orbitCurved celestial path
- fossaAnatomical depression or hollow
- glenoidShoulder's bony socket
- alveolusMicroscopic pulmonary chamber
sinus · ventricle · atrium · pelvis · cupped hand · arch · instep · navel
Underground hollow in rock
- cavernLarge natural underground chamber
- grottoSmall scenic cavern
- denPrivate room or lair
- burrowAnimal's dug dwelling
hole · chasm · ravine · canyon · gorge · valley · glen · dale
cavity
Empty space within
basin · depression · trough · dip · sinkhole · cenote · caldera · crater lake · pothole · hollow
socket
Hollow receiving cavity
alveolus · sinus · ventricle · atrium · pelvis · cupped hand · arch · instep · navel · dimple
cave
Underground hollow in rock
burrow · hole · chasm · ravine · canyon · gorge · valley · glen · dale · dell
groove
Narrow cut or routine
chamfer · rabbet · dado · mortise · notch · slot · keyway · gouge · carving · intaglio
curve
Smooth, angleless line
ellipse · camber · inflection · crescent · bowl · dish · lens · mirror · reflector · scoop
concavitiesconvexities
Outward-curving surfaces or shapes
bulges · protuberances · protrusions · bumps · bosses
concavitiesprotrusions
Things that jut out
projections · bumps · prominences · elevations · ridges