Meaning of IGNORANCE in English

IGNORANCE

[noun] [U]Public ignorance about AIDS is still a cause for concern.It's awful, the way these patients were left/kept in ignorance of what was actually wrong with them.(saying) 'Ignorance is bliss' means that you are often happiest if you do not know the true facts of a situation.

Cambridge English vocab.      Кембриджский английский словарь.