apse
arcade
arcature
arch
arched roof
archway
basis
bench mark
camber
cardinal point
ceilinged roof
chief thing
climax
concameration
concha
core
cornerstone
cove
crisis
critical point
crux
cupola
dome
essence
essential
essential matter
first stone
footstone
foundation
foundation stone
fundamental
geodesic dome
gist
gravamen
great point
headstone
heart
high point
igloo
important thing
issue
kernel
landmark
main point
main thing
material point
meat
milestone
necessity
nub
support
abutments
brucellosis
mini-van
nonnative
freestone