What term describes the failure to disclose or include important information?

The term that describes the failure to disclose or include important information is "Omission." Omission refers specifically to the act of leaving out or not including information that should be presented. In many contexts, especially legal and ethical ones, an omission can have significant consequences because it can lead to misunderstandings or decisions made without the full context of available information.

In contrast, "Exclusion" generally implies a deliberate choice to leave someone or something out but does not specifically highlight the failure to disclose information. "Negligence" involves a failure to take reasonable care in actions that could foreseeably harm others, which goes beyond just failing to disclose. "Concealment" refers to the act of deliberately hiding information, which suggests intent to mislead, rather than a mere failure to disclose. Thus, "Omission" is the most accurate term for the described scenario.