Duospaced font

A duospaced font (also called a duospace font) is a fixed-width font whose letters and characters occupy either of two integer multiples of a specified, fixed horizontal space. Traditionally, this means either a single or double character width.[1] although the term has also been applied to fonts using fixed character widths with another simple ratio between them.[2]

Visual comparison of a duospaced font (Migu 2M) versus a monospaced font (Consolas).

These dual character widths are also referred to as half-width and full-width, where a full-width character occupies double the width of a half-width character. This contrasts with variable-width fonts, where the letters and spacings have more than two different widths. And, unlike monospaced fonts, this means a character can occupy up to two effective character widths instead of a single character width. This extra horizontal space allows for the accommodation of wider glyphs, such as large ideographs, that cannot reasonably fit into the single character width of strictly uniform, monospaced font.

Although associated with Asian character sets and halfwidth and fullwidth forms, the general notion of duospaced fonts is not limited to such characters. Examples of duospaced characters not strictly associated with Asian halfwidth and fullwidth forms include various technical and pictographic symbols as seen in Migu 2M, and the Unicode character Roman Numeral One Hundred Thousand (U+2188) and various other symbols in GNU Unifont.