■ katakana, one of the Japanese syllabaries
In the ninth century, students trying to take lecture notes from 仏教 teachers using サンスクリット語 developed the かたかな。
A part of a 漢字 was broken off and formed into a かたかな。A typical example is カ /ka/ which comes from 加. In some cases, the 漢字 itself was simply modified or used as is to represent a かたかな。チ /chi/ is such an example, which comes from 千。In both of these cases, the pronunciations come from the 音読み of the 漢字。
Although a rare term today, 男手 refers to the 漢字 combined with かたかな, distinguishing them from 女手, the ひらがな, developed by and initially used by women.
Until the end of World War II, 漢字 and かたかな were the most common scripts. Then, the ひらがな came into common use with 漢字, leaving the かたかな for special use.
(2) Names of plants and animals
Especially in biological contexts. When the 漢字 have a meaning, it may be appealing to use 漢字。
白鳥 or ハクチョウ
(3) Other scientific or medical terms
As with plants and animals, かたかな is often used in medical and other scientific contexts. ひらがな and 漢字 are also often used.
(4) Any jargon
Any word that is specific to an industry or field or that has a special meaning in that field can be written in かたかな。The words actually used in this manner are limited in number, though this usage may differ according to company, industry or even personal preference.
カンバン kanban (a manufacturing term meaning sign in regular Japanese)
Similar to the use of italics in English. (See also emphasis marks). This use is particularly common in advertisements, magazines and 漫画 [future link].
Related to emphasis, this use gives the impression of someone actually speaking. Words in dialects are often written in かたかな.
ウチナンチュウ an Okinawan (from an Okinawan's point of view)
ヤマトンチュウ a non-Okinawan Japanese (from an Okinawan's point of view)
(7) Mimesis and onomatopoeia 擬声語・擬音語・擬態語
Particularly 擬声語 and 擬音語 [future links]. This use gives mimesis an impact.
The stone went tumbling down the hill (slope).
Although not used in everyday circumstances, dictionaries continue to use かたかな for 漢字 entries to indicate 音読み. Although most 音読み can be distinguished from 訓読み by the pronunciation, there are exceptions. When studying 漢字, it may be useful for the student of 日本語 to write 音読み using かたかな and 訓読み using ひらがな. This will help when learning 熟語.
When editing or proofing work, かたかな is common.
イキ stet (ignore the correction)
(10) Filling out forms
On forms asking for name and address information, there is frequently a ふりがな line. If the word ふりがな is written in ひらがな, ひらがな should be used by the person filling out the form. If it is written as フリガナ in かたかな, かたかな is to be used.
(11) To indicate a foreigner speaking Japanese
Ryouma, I wanted to see you!!
Yes, take a bath!!
(Both quotes from お〜い！竜馬 第五巻, by 武田鉄矢 and 小山ゆう, published by ヤングサンデーコミックス〈ワイド版〉
(12) The word かたかな itself is usually written カタカナ.
男手 otokode, literally man's hand. Also known as 男文字 otokomoji.
女手 onnade, literally woman's hand. Also known as 女文字 onnamoji.
音読み on'yomi, the Chinese reading of a 漢字. See 音読み
漢字 kanji, Japanese characters. See 漢字
訓読み kun'yomi, the native Japanese reading of a 漢字。See 訓読み
サンスクリット語 sansukuritto-go, Sanskrit. Also known as 梵語 bongo
熟語 jukugo, a compound 漢字 word. See 熟語
日本語 nihongo, the Japanese language
白鳥 hakuchou, swan
ひらがな hiragana, also written as 平仮名
仏教 bukkyou, Buddhism
振りがな furigana, kana used to indicate the pronunciation of 漢字。