A radical (in Japanese, 部首 bushu) is a character or a part of a character that functions as an element that determines the order in which kanji are listed in a character dictionary or index; radicals are analogous to the 26 initial letters in an alphabetical dictionary. But there are many more radicals, 214 or more in traditional Japanese dictionaries.
Each radical has its own meaning. With radicals that are characters in their own right, the meaning arises from the on reading of the character, while for the other radicals the meaning arises from traditional use.
Of the radicals in the 79-radical system, 49 are among the 1,945 Jōyō Kanji. The tables “The 214 Radicals and their Meaning” and “The 79 Radicals and their Meaning” (both in preparation) give an overview of the meanings of the 214 historical, and the 79 most important, radicals.
The function of a kanji’s radical is like that of the first letter of a word in an alphabetic dictionary: in an alphabetical dictionary, all words that begin with A are listed in the A section, while in a character dictionary, all kanji that contain 日 as a radical — such as 日、早、百、旬、旭、明、的、者、時、昼 — are listed under the radical 日 (sun). As shown in this example, kanji listed under the same radical are arranged in increasing order of their residual stroke count (the number of strokes of the pen the kanji is written with, apart from the number of strokes needed to write the radical itself).
As illustrated by the ten kanji shown in the preceding section “Function”, a radical can occur in various positions within a kanji. If a character contains two or more components that are listed in the radical table, which of them is the kanji’s radical is generally determined by where it is within the kanji. For example, the left side takes precedence over the right side in deciding which of two components is the radical of the kanji.
How many radicals are there?
The number of radicals used in modern character dictionaries varies between 79 and about 240. In most character dictionaries, the basis for the selection of radicals are the 214 radicals in the character dictionary 康熙字典 Kangxi zidian (Japanese title, Kōki jiten), which was published in 1716. The two most widely used Japanese-English kanji dictionaries (and their smaller learner’s version) by Nelson and by Spahn/Hadamitzky are arranged according to 214 and 79 radicals, respectively. These 79 radicals are – with a single exception – a subset of the 214 historical radicals.
Including variants of radicals in the count, the number of distinct radicals comes to about 400 in the 214-radical system, and to 136 in the 79-radical system.
Standard form and variants
Depending on where a radical appears within a kanji, the radical can assume different forms that make it hard to identify. Radicals can vary in size, proportions, stroke sequence, and appearance. For example, the radical for “person” has the form 人 when it stands alone and in many kanji, but has the form 亻 when it is the left-hand component of a kanji; and with the radical for water there is a particularly big difference between its stand-alone form 水 and its left-side-of-the-kanji form氵, even in its number of strokes (4 versus 3). What is listed as the standard form of a radical in the radical tables of character dictionaries is either the form that is itself a stand-alone kanji, or the form that occurs most frequently. Forms of a radical that deviate from the standard form are called variants.
Traditionally the radicals are arranged in order of increasing stroke count, and among radicals of the same stroke count, they are listed according to their order in the Kangxi zidian. Since this order among same-stroke-count radicals in the traditional sequence is apparently arbitrary, Chinese dictionaries and those that follow the 79-radical system organize these radicals more systematically, according to the position of the radical within the kanji, to allow the user to find the sought radical more quickly: In the 79-radical system, among radicals of the same stroke count, those that usually appear on the left side of the kanji are listed first, followed those that appear on the right, on the top, on the bottom, and as an enclosure around the rest of the kanji. Beyond this sub-ordering, radicals having the same stroke count and the same position within the kanji are ordered according to their frequency.
A table of the radicals and their variants that are used in a character dictionary is usually found inside the front or back cover of the dictionary. This table also functions as an index, giving for each radical the place in the dictionary where the entries begin that are classified under that radical.
On the page Radical tables are typical tables from dictionaries with 79 and 214 radicals. These tables give information about the radicals and the sequence in which they are arranged.
Determining the radical of a kanji
Most kanji have two or more constituent parts that are listed in the radical table and that thus could theoretically be the kanji’s radical. But to save space, character dictionaries list kanji only under one of these constituent parts. Traditional character dictionaries follow a tradition that dictates which part of the kanji is its radical, while modern works set forth unambiguous rules to specify which part of a kanji is its radical.
Traditional character dictionaries list the characters under the same radical as in the Kangxi zidian dictionary of 1716. This presents the user with two problems. First, the Kangxi zidian prescribes its 214 radicals according to hard-to-understand criteria such as etymology that are not explained even in the newest dictionaries that follow this sequence of radicals. Second, this provides no solution for the many kanji used today that are simplified from their original form, simplified in such a way that their original radical has disappeared. The result is that many kanji are classified under different radicals in different dictionaries, with no clear explanation for the classification.
By contrast, since the beginning of the 20th century, character dictionaries for foreigners have set forth clear rules for determining the radical of a kanji. Noteworthy here are the Japanese-English character dictionaries by Rose-Innes (1924), Nelson (1962), and Spahn/Hadamitzky (1989). In all three of these works the radical is determined by its position within the radical: in Nelson* according to the Radical Priority System, and in Spahn/Hadamitzky according to a Checklist for determining the radical of a kanji.
* In the “New Nelson” (1997) the Radical Priority System has been replaced by the traditional ordering of the kanji.
Radical systems are lexicographic ordering systems that help the user find a kanji or multi-kanji word quickly by radical in character dictionaries. A radical system consists of two components: a list of radicals (Radical tables), and Rules for determining the radical of a kanji. For more about this, see the article “Radical systems” (in preparation).
Even the oldest Chinese dictionary that has survived intact, the 説文解字 (Shuowen jiezi; in Japanese, Setsumon kaiji), which appeared in the year 121, orders its mere 10,000 kanji under 540 部首 (radicals).
September 2005, W.H. with Mark Spahn