Definition from Wiktionary, the free dictionary
fullwidth (not comparable)
- (computing, typography, of certain characters) 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.
Usually, fullwidth characters are used to match the space taken up by characters – particularly Chinese characters – in certain other languages such as Japanese.
occupying two columns on a traditional text display
Letters in fullwidth form