concavity (n.)
- alveolus
- antrum
- arching
- armpit
- basin
- boss
- bowl
- bump
- cavity
- circularity
- colophon
- convexity
- convolution
- crater
- crookedness
- crypt
- cup
- curvation
- curvature
- de-escalation
- debasement
- degradation
- demotion
- dent
- depression
- descent
- diminution
- dint
- dip
- ducking
- embossment
- excrescence
- fingerprint
- fold
- follicle
- footmark
- footprint
- footstep
- hole
- hollow
- hollowness
- impress
- impression
- imprint
- incurvation
- incurvature
- indent
- indentation
- indention
- lacuna
- lowering
- lump
- pad
- pimple
- pit
- pug
- reduction
- rotundity
- sag
- scoop
- seal
- shell
- signet
- sink
- sinkhole
- sinking
- sinuosity
- sinuousness
- sinus
- socket
- stamp
- step
- stud
- submergence
- thumbprint
- tortuosity
- tortuousness
- trough
- vaulting
- vestige
