axiom
bench mark
best part
better part
body
bulk
cardinal point
center
chief thing
climax
core
cornerstone
crisis
critical point
crux
elixir
essence
essential
essential matter
flower
focus
fundamental
generality
gist
great point
heart
high point
hypostasis
important thing
inner essence
issue
kernel
keystone
landmark
main body
main point
main thing
major part
majority
marrow
mass
material point
meat
milestone
most
nub
nucleus
nuts and bolts
pith
pivot