The word 保密 is formed by combining two meaningful characters into a single conceptual unit. The first character, 保 (bǎo), carries the core idea of "protecting" or "preserving". It is joined with the second character, 密 (mì), which means "secret" or "confidential". Together, they do not simply list two ideas but interact to create a new, composite meaning: the action or state of "protecting a secret", which equates to "maintaining secrecy" or "confidentiality". It is a direct, logical fusion where 保 acts upon 密, much like building blocks that, when connected, form a specific and practical concept.