Modern examples particularly include Chinese characters for SI units. In Chinese these units are disyllabic and standardly written with two characters, as 厘米 límǐ "centimeter" (厘 centi-, 米 meter) or 千瓦 qiānwǎ "kilowatt". However, in the 19th century these were often written via compound characters, pronounced disyllabically, such as 瓩 for 千瓦 or 糎 for 厘米 – some of these characters were also used in Japan, where they were pronounced with borrowed European readings instead. These have now fallen out of general use, but are occasionally seen. Less systematic examples include 圕 túshūguǎn "library", a contraction of 圖書館, A four-morpheme word, 社会主义 shèhuì zhǔyì "socialism", is commonly written with a single character formed by combining the last character, 义, with the radical of the first, 社, yielding roughly 礻义.

What are disyllabic and usually written with two characters?