ig·no·rance 
/ˈɪgnərəns/ noun
/ˈɪgnərəns/ noun : a lack of knowledge, understanding, or education : the state of being ignorant [noncount] ▪ His racist attitudes were born out of ignorance. — often + of ▪ Ignorance of the law is no excuse (for violating it). ▪ Their decisions were made in ignorance of [=without knowing] the true nature of the situation. ▪ When asked about the reasons for these drastic changes, she pleaded/pled ignorance. [=she said that she did not know the reasons] [singular] ▪ an appalling ignorance about/of other cultures
ignorance is bliss
— used to say that a person who does not know about a problem does not worry about it
