不 - negative, non-, bad

of uncertain meaning; ambiguous; cryptic; nonsensical; incomprehensible; perplexing

anxiety; uneasiness; worry; apprehension; fear; insecurity; suspense

unpleasant; disagreeable; displeasing; uncomfortable; unhappy

suddenly; abruptly; unexpectedly

heart failure

lack of filial piety; disobedience to one's parents

lack of physical exercise; insufficient exercise; inactivity

disadvantage; handicap; unfavorable position

unhappiness; misfortune; ill luck

infertility; sterility; barrenness

missing (of a person); lost; unaccounted for; whereabouts unknown

sudden; abrupt; unexpected; unforeseen