unpalatable
unpleasant
unheralded
little known, unexpected
unparalleled
unique, with no equal
unstinting
giving freely ang generously
untenable
impossible to defend
untimely
out of the natural or proper time
unyielding
resolute, firm, obdurate
unsurper
someone who takes a place or possession without the right to do so
utilitarian
purely or practical benefit
utopia
an imaginary, perfect society