over the rainbow
unattainable
unreachable
unachievability
beyond one's pay grade
reachless
un-come-at-able
ungetatable
un-get-at-able
ungraspable
graspless
approachless
unachievable
unrealizable
maxed-out
undoable
unaccessible
inaccessible
unattainability
punch above
reachlessness
impossibly
untranscendable
unably
reachability
run to
max out
if the mountain won't come to Muhammad
tether
insuperable
unsuperable
unescapability
unstanchable
unmusterable
insurmountable
rub
unsurmountable
hang-up
Matterhorn
snag
unscalable
inscrutable
hitch
huckleberry above one's persimmon
stumblingblock
ambitious
unrealized
outreach
impassable
elusiveness