不 - negative, non-, bad

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

defect; deficiency; imperfection; inadequacy; lack

suddenly; abruptly; unexpectedly

discord; dissonance; cacophony

(economic) depression; recession; slump

not asking (about); letting go unquestioned; disregarding; ignoring; overlooking

unhappiness; misfortune; ill luck

infertility; sterility; barrenness

non-inflammables; incombustible (usu. waste)

uncertainty; insecurity; inconstancy; indefinite; undecided

indecisive; irresolute; shilly-shally; vacillating

heart failure