1. base, basis, cornerstone, foundation, fundament, groundwork

the fundamental assumptions from which something is begun or developed or calculated or explained

Example Sentences:
'the whole argument rested on a basis of conjecture'

Synonyms

• base
• basis
• cornerstone
• foundation
• groundwork

2. arse, ass, backside, behind, bottom, bum, buns, butt, buttocks, can, derriere, fanny, fundament, hind end, hindquarters, keister, nates, posterior, prat, rear, rear end, rump, seat, stern, tail, tail end, tooshie, tush

the fleshy part of the human body that you sit on

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

Synonyms

• arse
• ass
• backside
• behind
• bottom
• bum
• buns
• butt
• buttocks
• can
• derriere
• fanny
• hind end
• hindquarters
• keister
• nates
• posterior
• prat
• rear
• rear end
• rump
• seat
• stern
• tail
• tail end
• tooshie
• tush

3. base, foot, foundation, fundament, groundwork, substructure, understructure

lowest support of a structure

Example Sentences:
'it was built on a base of solid rock'
'he stood at the foot of the tower'

Synonyms

• base
• foot
• foundation
• groundwork
• substructure
• understructure