unacknowledged
unrewarding
nonexistent
unanswered
unattempted
unavailable
uncared
uncollected
unconsidered
underfed
undetected
undreamed-of
unexplored
unheard
unheralded
unrecognised
unrecognized
unrecorded
unremarked
unremembered
unreported
unrepresented
unrewarded
untapped
unvalued
appreciated
depreciated