unidentifiable
black-looking
costless
different
fine-material
foolproof
frictionless
gold-framed
ineluctable
landlocked
nose-to-nose
off-guard
shadow-like
silvery-haired
soundproof
undetectable
undistinguishable
uninhabitable
unnoticeable
unobtainable
unplayable
unrecognizable
unselfconscious
unusable
valueless