唯

Pure Classical Chinese — a subordinate's immediate, deferential 'aye' to a superior, contrasted in the Analects with the slower 诺 ('yes') used among equals. Never used in modern speech; appears only when reading or quoting pre-modern texts. The 'only' adverb 唯 is the everyday reading and what learners will encounter 99% of the time.

This assent-particle reading is often treated as the etymological root of the modern 'only' sense: a single decisive 'yes' generalised to 'singularly, solely'. The mouth radical 口 in 唯 preserves the speech-act origin even though no one says wěi aloud anymore.