In certain cases compound words and set phrases may be contracted into single characters. Some of these can be considered logograms, where characters represent whole words rather than syllable-morphemes, though these are generally instead considered ligatures or abbreviations (similar to scribal abbreviations, such as & for "et"), and as non-standard. These do see use, particularly in handwriting or decoration, but also in some cases in print. In Chinese, these ligatures are called héwén (合文), héshū (合書) or hétǐzì (合体字), and in the special case of combining two characters, these are known as "two-syllable Chinese characters" (双音节汉字, 雙音節漢字).
A commonly seen example is the double happiness symbol 囍, formed as a ligature of 喜喜 and referred to by its disyllabic name (simplified Chinese: 双喜; traditional Chinese: 雙喜; pinyin: shuāngxǐ). In handwriting, numbers are very frequently squeezed into one space or combined – common ligatures include 廿 niàn, "twenty", normally read as 二十 èrshí, 卅 sà, "thirty", normally read as 三十 sānshí, and 卌 xì "forty", normally read as 四十 "sìshí". Calendars often use numeral ligatures in order to save space; for example, the "21st of March" can be read as 三月廿一. In some cases counters are also merged into one character, such as 七十人 qīshí rén "seventy people". Another common abbreviation is 门 with a "T" written inside it, for 問題, 问题, wèntí ("question; problem"), where the "T" is from pinyin for the second syllable tí 题. Since polysyllabic characters are often non-standard, they are often excluded in character dictionaries.
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.
The use of such contractions is as old as Chinese characters themselves, and they have frequently been found in religious or ritual use. In the Oracle Bone script, personal names, ritual items, and even phrases such as 受又(祐) shòu yòu "receive blessings" are commonly contracted into single characters. A dramatic example is that in medieval manuscripts 菩薩 púsà "bodhisattva" (simplified: 菩萨) is sometimes written with a single character formed of a 2×2 grid of four 十 (derived from the grass radical over two 十). However, for the sake of consistency and standardization, the CPC seeks to limit the use of such polysyllabic characters in public writing to ensure that every character only has one syllable.