undersurface
Lower exposed area
The undersurface is the bottom or lower side of something—the part facing down or away from view: the undersurface of a leaf, the undersurface of the wing.
The term appears most often in scientific or technical contexts describing anatomy, aircraft, or natural objects.
Vulnerable lower surface
palm · plantar · abdominal · inferior · lower · basal · beneath · nether
Underlying supporting material
- underlayerStratum beneath another
- subfloorBase beneath finished flooring
- baseplateStructural bottom piece
- substratumFoundational layer beneath
underpinning · substructure · footing · foundation · bedrock · groundwork · sill · plinth
underbelly
Vulnerable lower surface
underfoot · palm · plantar · abdominal · inferior · lower · basal · beneath · nether · underpart
substrate
Underlying supporting material
- underlayerStratum beneath another
- subfloorBase beneath finished flooring
- baseplateStructural bottom piece
substratum · underpinning · substructure · footing · foundation · bedrock · groundwork · sill · plinth · undercoating
hidden
Kept out of sight
undetected · latent · underlying · buried · covered · unexposed · submerged · veiled · masked · covert