from Wiktionary, Creative Commons Attribution/Share-Alike License
- adj. Occupying two columns on a traditional text display such as kanji, as opposed to halfwidth occupying only one column such as alphanumeric letters. Some characters have both forms: for example katakana ka has the fullwidth カ and the halfwidth ｶ.
Calque of Japanese 全角, zenkaku. (Wiktionary)