Derivation by tone change refers to a type of word formation in which a new word is derived by changing the tone of the original word. For example, yī 衣 (MC *’jɨj, level tone) is a noun meaning ‘clothing’. The changed-tone word yì 衣 (MC *’jɨjH, departing tone) is the derived verb ‘to wear (clothes), to clothe’. This type of derivation is systematic. For example, guān 冠 (MC *kwan, level tone) is a noun meaning ‘cap’, and the changed-tone word guàn 冠 (MC *kwanH, departing tone) is a verb meaning ‘to wear (a cap)’. (Middle Chinese reconstructions are given in the system of Baxter 1992.)

Historically, …