A more thorough explanation:

Definition: Crassa ignorantia (kras-uh ig-nuh-ran-shee-uh) is a historical term that refers to gross ignorance, especially in circumstances where a person had the opportunity to gain knowledge but failed to do so.

Examples:

• A doctor who refuses to learn about new medical treatments and continues to use outdated methods is exhibiting crassa ignorantia.
• A student who skips class and fails to study for exams despite having access to educational resources is also displaying crassa ignorantia.

These examples illustrate how crassa ignorantia is not just a lack of knowledge, but a willful neglect of opportunities to learn and improve oneself. It is a failure to take responsibility for one's own education and growth.