Ignorance is a state of being uninformed. This should not be confused with being unintelligent, as one's level of intelligence and level of education or general awareness are not the same. The word "ignorant" is an adjective describing a person in the state of being unaware. The term may be used specifically (e.g. "One can be an expert in math, and totally ignorant of history.") or generally (e.g. "an ignorant person.")—although the second use is used less as a descriptive and more as an imprecise personal insult.

The legal principle that ignorantia juris non excusat, literally "ignorance of the law is no excuse", stands for the proposition that the law applies also to those who are unaware of it.