bottom of one's heart;  depths of one's mind;  innermost thoughts;  from the bottom of one's heart;  wholeheartedly;  truly
 (cannot) possibly;  (not) by any means;  (not) at all;  utterly;  absolutely
 thorough;  exhaustive;  complete
 thoroughness;  completeness;  consistency;  thorough enforcement;  seeing to it that a policy, etc. is carried out without exception
 bottom of the ocean;  seafloor;  seabed;  undersea;  submarine
 depths;  deep place;  bottom (of one's heart)
 base (e.g. of a triangle);  low class;  low in social standing;  base (e.g. of support);  foundation
 palm heel;  heel of the palm
 underground lake;  subterranean lake
 original text;  source book;  draft
 do-or-die resistance;  resistance to the bitter end
 base (logarithmic, exponential, number system);  radix;  base (triangle, cone, cylinder, etc.);  type;  kind
 shortage;  scarcity;  dearth;  famine
 the bottom of one's heart
 inconsistent;  illogical;  unconvincing;  not thorough;  indefinite;  half-way
 bottom current;  undercurrent
 dissemination;  spreading of information
 being connected at a fundamental level;  having an unseen commonality;  underlying (both)
 undersea cable;  submarine cable
 planta;  planta pedis;  sole of the foot
 lower classes;  proletariat;  underclass
 basal ganglia;  basal nuclei
 well bottom;  narrow place
 attain divine enlightenment;  perceive absolute truth;  experience spiritual awakening
 lower brain;  base of the brain
 seabed probe;  probe of the ocean floor;  submarine prospecting
 orbital floor (thin bone floor of eye socket)
 thorough investigation;  complete inquiry
 hemorrhage in the fundus of the eye;  hemorrhage in the eyeground
 totally useless (fruitless) effort;  wasting time on an impossible task (like trying to scoop up a reflected moon from the bottom of the sea)
 undersea cable (communications, power);  submarine cable
 funduscopy;  fundus examination;  ophthalmoscopy
 bottom depths (of water);  abyss;  depths (of something);  bottom; (arch.)  completely; (arch.)  thoroughly
 base structure;  underlying structure
 submarine valley;  submarine canyon
 pelvic floor muscle;  pubococcygeal muscle;  Kegel muscle
 basal ganglia;  basal nuclei
 benthic organism;  sea-bottom fauna;  benthos
 do your best;  give it your all
 basement membrane;  basal lamina
 benthic animal;  benthonic animal;  zoobenthos
 floating-point base;  floating-point radix
 mixed base (numeration) system;  mixed base notation
 mixed base (numeration) system;  mixed base notation
 abnormal cerebrovascular network in the cerebral basal region
 bottom water (depth: 4000+ meters)
 phlegmon in floor of oral cavity;  Ludwig's angina
 local basis;  localized basis
 bottom material;  bed material;  sludge;  sediment;  substratum
 ocean floor;  sea floor;  seabed