nonreciprocal
unrequited
unappreciated
unattained
unattempted
unchallenged
undelivered
undetected
undiscovered
unexamined
unexplained
unexplored
unguessed
unharmed
unheard
unheeded
unread
unremembered
unrepresented
unrevealed
unsay
unsolved
unspoken
untapped
untrodden
unvoiced
Hansard
answered