fundament
1. [ noun ] the fleshy part of the human body that you sit on
Synonyms: seat ass bottom rear_end tail behind buttocks stern hind_end hindquarters keister posterior bum backside prat rear buns tail_end tooshie tush rump can derriere fanny butt nates arse
Examples:

"he deserves a good kick in the butt" "are you going to sit on your fanny and do nothing?"

Related terms: body_part torso
2. [ noun ] the fundamental assumptions from which something is begun or developed or calculated or explained
Synonyms: basis base groundwork cornerstone foundation
Examples:

"the whole argument rested on a basis of conjecture"

Related terms: assumption meat_and_potatoes explanation
3. [ noun ] lowest support of a structure
Synonyms: base foot foundation substructure understructure groundwork
Examples:

"it was built on a base of solid rock" "he stood at the foot of the tower"

Related terms: support raft_foundation bed structure
Similar spelling:   fundamental
  fundamentals