Learner's definition of IGNORANCE
: a lack of knowledge, understanding, or education: the state of being ignorant
[noncount]— 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]
ignorance is bliss
— used to say that a person who does not know about a problem does not worry about it