密碼 (mìmǎ) literally combines 密 (mì), meaning 'secret' or 'confidential', and 碼 (mǎ), meaning 'code' or 'cipher'. Together, they form the standard modern Chinese term for 'password' — a secret string of characters used to verify identity or grant access to digital accounts, devices, or secure systems. It is widely used in computing, banking, and online services, and carries no classical or literary connotation; it is a purely functional, contemporary compound.

The word appears in both formal and casual contexts — from login screens and security settings to everyday conversations about account recovery or app setup. Unlike some English synonyms (e.g., 'passphrase'), 密碼 always refers to a concise, often alphanumeric sequence, not a full sentence. It is never used metaphorically for personal secrets outside the realm of authentication, and does not imply encryption algorithms themselves — only the user-supplied key.