underswell

English

Etymology

under- +‎ swell

Noun

underswell (plural underswells)

1. An undercurrent.
2. A swelling undersection.
   • 1963, J. G. Ballard, Passport to Eternity:

     Something had altered the normal perspectives of the room. Trying to focus on the grey underswell of the ceiling, I listened for footsteps outside. Sure enough, the corridor wall began to retract.